Electronic correlations and partial gap in the bilayer nickelate La$_{3}$Ni$_{2}$O$_{7}$

Hai-Hu Wen; Jiahao Hao; Jie Li; Meng Wang; Mengwu Huo; Qing Li; Xiaoxiang Zhou; Yaomin Dai; Yi Lu; Yuecong Liu

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Electronic correlations and partial gap in the bilayer nickelate La$_{3}$Ni$_{2}$O$_{7}$

Zhe Liu, Mengwu Huo, Jie Li, Qing Li, Yuecong Liu, Yaomin Dai, Xiaoxiang Zhou, Jiahao Hao

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Yi Lu, Meng Wang, Hai-Hu Wen

Superconductivity · Submitted 6 Jul 2023 · 68 references

Pith's verdict: Solid ambient-pressure optics on La3Ni2O7 with a genuinely new two-Drude result; the correlation number and the orbital assignment are softer than the abstract implies, but the qualitative story holds.

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CitationHai-Hu Wen, Jiahao Hao, Jie Li, Meng Wang, Mengwu Huo, Qing Li, Xiaoxiang Zhou, Yaomin Dai, Yi Lu, Yuecong Liu, Zhe Liu. "Electronic correlations and partial gap in the bilayer nickelate La$_{3}$Ni$_{2}$O$_{7}$." arXiv:2307.02950 (2023). https://pith.science/paper/UFMK4THM

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Editor's note

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The thing worth your time here is the two-Drude decomposition and its temperature dependence. The authors measure ab-plane reflectivity on La3Ni2O7 from 30 to 50,000 cm-1, Kramers-Kronig it, and show that below T* = 115 K one Drude channel (D2, linear-in-T scattering) collapses while the other (D1, quadratic) is essentially untouched. That is a clean, physically specific observation, and it lines up with the transport resistivity and with the spectral-weight ratio S(5 K)/S(125 K), which are independent of the fit. The 115 K anomaly itself is not new, but resolving it into an orbital-selective removal of one Fermi-surface sheet is. The Kexp/Kband = 0.022 estimate is also new for this compound and puts it near the cuprates on the correlation axis, which is a useful number for the field regardless of how the orbital story lands. The paper is appropriately hedged on the d3z2-r2 assignment (abstract:s6 says 'suggest'), and it flags that temperature-dependent ARPES is needed to confirm it. That is honest framing, not overreach. Where I would push back: the seven-component fit (two Drude plus L1-L4 and LH) carries both the D2 weight and the Kexp/Kband number, and the paper itself says intraband and interband weight 'strongly overlap.' No uncertainties or alternative-fit comparison are given, so the two routes to 0.022 are a consistency check, not independent confirmation. The stress-test note is right about that. It is less right about 1/tau_D2 being unconstrained below T*: the non-Fermi-liquid claim is a statement about the normal state above the transition, where D2 has weight, so the vanishing-weight regime does not undercut it. The gap extraction (2Delta = 100.5 meV from the zero crossing of Delta sigma_1, referenced to 125 K) is a coarse estimator, and the short-coherence-length reading of 2Delta/kBT* = 10.14 is plausible but untested. None of this is structural. Even a factor-of-two error in the fit leaves La3Ni2O7 deeply correlated and comparable to doped cuprates, so the headline conclusion survives the softness in the number. Who should read it: anyone working on the nickelates, and anyone using optical conductivity to argue about orbital-selective correlations. It deserves referees, mainly to force an error bar onto the fit and a sensitivity check on the interband subtraction.

Referee report

Significance

If correct, this is a useful and timely contribution: it establishes that the ambient-pressure density-wave-like transition in La$_3$Ni$_2$O$_7$ is orbital-selective, and it identifies the strongly correlated Ni-$d_{3z^2-r^2}$ flat band as the part of the electronic structure that competes with superconductivity under pressure. The strengths are real and should be named. The spectral-weight-ratio analysis of Fig. 4a is essentially model-independent and is the most convincing single piece of evidence in the paper: $S(5$ K$)/S(125$ K$)$ dips below unity near 600 cm$^{-1}$ and recovers at 6500 cm$^{-1}$, and this does not depend on the seven-component fit. The transport/optics cross-check in Fig. 1a is well done. The paper also makes a falsifiable prediction — that temperature-dependent ARPES should see the $γ$ band cross $E_F$ at $T^*$ — which is exactly the right way to close the argument, and the authors say so explicitly in the Discussion. The comparison with LaNiO$_2$ (Hund's metal, $K_{DMFT}/K_{DFT} = 0.5$–$0.6$, opposite orbital ordering of correlation strength) is a genuinely informative contrast.

Major objections (4)

[Results, 'Drude-Lorentz analysis and theoretical calculations'; Fig. 2a; Supplementary Table 1] The load-bearing decomposition of $σ_1(ω)$ into two Drude terms plus five Lorentzians is presented without any uncertainty quantification, covariance information, or alternative-fit comparison. The manuscript itself states that 'the intraband and interband excitations strongly overlap with each other,' and the low-lying Lorentzians L1 and L2 sit close to the D2 scale, so weight can be traded between D2 and L1/L2 with little change in $χ^2$. Every downstream quantity that carries the central claim — $ω_{p,D2}^2(T)$, $1/τ_{D2}(T)$, and $K_{exp}$ — inherits this ambiguity. Please report fit uncertainties (e.g., from a covariance or bootstrap analysis of Supplementary Table 1), and demonstrate that the temperature dependence of $ω_{p,D2}^2$ survives when the low-lying Lorentzian positions and widths are constrained, for instance by fixing them from the high-temperature spectra where D2 has collapsed. A statement of how much D2 weight can be moved into L1/L2 before the fit quality degrades would go a long way toward making the orbital-selective claim convincing.
[Results, 'Electron's kinetic energy and electronic correlations'; Eq. (2); Supplementary Figs. 3 and 4] The value $K_{exp}/K_{band} = 0.022$ is the basis for the 'proximity to the Mott phase' claim, and it is derived from a model-dependent interband subtraction (Supplementary Fig. 3) followed by an integral to $ω_c = 3000$ cm$^{-1}$. Two issues need addressing. First, the two routes to $K_{exp}/K_{band}$ (the Eq. 2 integral and the $ω_{p,exp}/ω_{p,cal}$ ratio) are not independent: both use the same Drude-Lorentz fit, so the stated agreement is a consistency check rather than external validation, and the manuscript should say so. Second, the claim that the result is insensitive to $ω_c$ 'provided it covers the entire Drude response' is precisely what is ambiguous when the Drude and interband responses overlap. Please propagate a systematic uncertainty on $K_{exp}/K_{band}$ — for example, by quoting the value obtained if the low-lying Lorentzians are allowed to absorb an additional 10–20% of the low-frequency weight — and state whether the qualitative conclusion ('near the Mott phase,' 'comparable to doped cuprates') survives at the upper end of that range. The comparison in Fig. 2d also draws values for other materials from Ref. [32], which used different cutoffs and subtraction procedures; a sentence acknowledging that these are not strictly like-for-like comparisons would be appropriate.
[Discussion, paragraphs 2–3; Fig. 2b; abstract sentence s6] The identification of the removed Fermi surface with the Ni-$d_{3z^2-r^2}$-derived flat band is an inference built from three ingredients: the DFT band structure of the nonmagnetic Amam phase, the published ARPES result of Ref. [42] at 18 K, and the correlation-strength argument that the more strongly correlated orbital should show non-Fermi-liquid behavior. None of these is a direct orbital-sensitive measurement in this data set, and the DFT band structure used for the orbital assignment is computed for the high-temperature phase, whereas the state below $T^*$ is a density wave in which the bands are reconstructed. The manuscript should address explicitly whether a nesting-driven reconstruction of the Ni-$d_{x^2-y^2}$-derived sheets, or a reconstruction that mixes orbital character at the avoided crossings near $S(R)$, could produce the same optical signature (loss of one Drude component with linear-in-$T$ scattering, weight transfer to 6500 cm$^{-1}$). If the data cannot discriminate, the abstract's 'suggest' is appropriately hedged but the Discussion should say what measurement would settle it.
[Results, 'Energy scale of the spectral weight redistribution'; Fig. 4b and 4f] The gap is extracted as the zero-crossing of $Δσ_1(ω) = σ_1^{T<T^*}(ω) - σ_1^{125 K}(ω)$, giving $2Δ = 100.5$ meV and $2Δ/k_BT^* = 10.14$. A zero-crossing of a difference spectrum is not a direct measure of a gap edge when, as Fig. 4a shows, the lost weight is redistributed over a range extending to 6500 cm$^{-1}$ — roughly eight times the quoted $2Δ$. Please justify why the crossing point should be identified with $2Δ$ rather than with the energy at which the redistribution changes sign, give an uncertainty on $2Δ$ that reflects the choice of normal-state reference (125 K versus, say, 150 K), and state how $Δ(T)$ in Fig. 4f is obtained at each temperature and with what error bar. The agreement with the ARPES value of ~50 meV (Ref. [42]) is suggestive but should not be presented as confirmation until the extraction systematic is quantified.

Minor objections (7)

[Fig. 3c] The temperature range over which $1/τ_{D1} ∝ T^2$ is fitted, and the fitted coefficient, should be stated in the caption or text; the range matters for the Fermi-liquid characterization.
[Discussion, paragraph 2] The statement that the remaining Ni-$d_{x^2-y^2}$-dominated Fermi surface has 'quarter filling ... corresponding to the heavily overdoped regime in the phase diagram for hole-doped cuprates' is an analogy, not a derived result; it should be flagged as such in the sentence itself.
[References] Ref. [33] (Geisler et al., a high-pressure optical study of La$_3$Ni$_2$O$_{7-δ}$) is cited only in passing for electronic correlations. Since it is the most directly comparable optical work, a short quantitative comparison of the two studies' correlation estimates and Drude decompositions would strengthen the Discussion.
[Eq. (1) and its surrounding text] The definition $ω_p^2 = Z_0 n e^2/2πm^*$ together with the prefactor $2πZ_0$ in Eq. (1) is easy to misread; a one-line dimensional check, or a statement of the convention used for $ω_p$ in Supplementary Table 1, would help readers compare with other optical papers.
[Results, 'Reflectivity and optical conductivity'; Fig. 1b–c] The captions note the vertical offsets applied below 125 K, but the reader cannot tell which curves correspond to 5 K and 125 K, the two temperatures used throughout Fig. 4. Labelling those two curves explicitly would help.
[Results, 'Electron's kinetic energy...'; Supplementary Fig. 3] The interband subtraction procedure is described only in the Supplementary Material. A single sentence in the main text explaining how $σ_1^{inter}(ω)$ is constructed would make the $K_{exp}$ determination self-contained.
[Abstract, sentence s4] 'Two Drude components arising from multiple bands at the Fermi level' reads as a measured assignment; the band attribution is from DFT plus published ARPES. Consider softening to make clear which part is measured and which is inferred.

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The paper

The paper claims

Two kinds of electron fluid coexist in La3Ni2O7, and the 115 K transition removes only one of them.

The reading

La3Ni2O7 becomes superconducting near 80 K only under pressure, but at ambient pressure it hosts a transition at $T^{ast} simeq 115$ K that has been guessed to be a charge or spin density wave. This paper asks what that transition does to the electrons that carry current, using infrared reflectivity and the optical conductivity it yields. The authors find the low-frequency response needs two separate Drude components, one whose scattering rate grows as $T^2$ (Fermi-liquid-like) and one that grows linearly in $T$ (non-Fermi-liquid-like); below $T^{ast}$ the second one disappears while the first barely moves. Comparing the measured Drude weight with band theory gives a kinetic-energy ratio $K_{exp}/K_{band} = 0.022$, putting the material close to a Mott insulator, so the vanishing component is plausibly the flat, strongly correlated band of Ni-$d_{3z^{2}-r^{2}}$ character. If this reading holds, the ambient-pressure ordering is orbital-selective: it knocks out exactly the piece of Fermi surface that theory flags as most correlated, and that is the piece superconductivity has to contend with.

What carries the argument

The argument rests on decomposing the measured $sigma_1(omega)$ into a Drude-Lorentz model: two Drude terms for the free carriers plus five Lorentz oscillators (L1, L2, L3, L4, LH) for interband transitions. The two Drude terms carry the physical claim, since their separate plasma frequencies and scattering rates are what distinguish the two Fermi-surface sheets and their different temperature laws. The second piece of machinery is the kinetic-energy ratio $K_{exp}/K_{band}$, obtained two ways that agree: by integrating $sigma_1^{total} - sigma_1^{inter}$ up to $omega_c = 3000$ cm$^{-1}$ and comparing with the band-theory value, and by comparing the measured plasma frequency $omega_{p,exp} = 3854$ cm$^{-1}$ with the calculated $omega_{p,cal} = 3.22$ eV. Both give 0.022, which is the number that places La3Ni2O7 next to the doped cuprates and near the Mott phase on the correlation-strength scale.

Extended reading notes

Core claim

The paper reports that the optical conductivity of La3Ni2O7 at low frequency cannot be fit with a single Drude term; it requires two, with distinct temperature behaviours. The first, D1, has a scattering rate following $1/ au_{D1} propto T^2$ over a broad range, the signature of a Fermi liquid. The second, D2, follows $1/ au_{D2} propto T$, the signature of a non-Fermi liquid. Cooling through $T^{ast} simeq 115$ K abruptly suppresses the D2 weight $omega_{p,D2}^2$ until it vanishes, transfers spectral weight from below roughly 600 cm$^{-1}$ up to about 6500 cm$^{-1}$, and leaves $omega_{p,D1}^2$ essentially unchanged. The authors extract a gap scale from the difference conductivity, $2Delta = 100.5$ meV, i.e. $2Delta/k_BT^{ast} = 10.14$, far above the weak-coupling BCS value of 3.52, and note that the gap's temperature dependence departs from BCS mean field near $T^{ast}$. Combined with their band-structure calculation, in which a flat hole-like Ni-$d_{3z^{2}-r^{2}}$ band and broad electron-like Ni-$d_{x^{2}-y^{2}}$ bands both cross the Fermi level, they conclude that the transition removes the Fermi-surface sheet dominated by the Ni-$d_{3z^{2}-r^{2}}$ orbital.

Load-bearing premise

The seven-component Drude-Lorentz fit cleanly separates free-carrier from interband spectral weight, even though the authors themselves state that the intraband and interband excitations strongly overlap, so both the two-Drude assignment and the 0.022 correlation ratio depend on that separation being right.

Editorial extensions

If this is right

The density-wave-like transition at $T^{ast}$ is orbital-selective rather than a wholesale reconstruction of the Fermi surface, since one Drude channel survives intact.
The correlation strength of La3Ni2O7, $K_{exp}/K_{band} = 0.022$, is comparable to doped cuprates and much stronger than in iron-based superconductors, which is offered as a hint that its high-$T_c$ physics is correlation-driven.
The large ratio $2Delta/k_BT^{ast} = 10.14$ implies a short coherence length for the ordered state and therefore strong critical fluctuations near $T^{ast}$, which the authors invoke to explain the non-mean-field temperature dependence of the gap.
Because the surviving Fermi-liquid pocket is Ni-$d_{x^{2}-y^{2}}$-dominated and near quarter filling, it maps onto the heavily overdoped cuprate regime where a Fermi liquid persists despite strong correlations.
A simple temperature-induced shift of the Fermi level is argued to be excluded, because the Drude weight drops abruptly at $T^{ast}$ rather than decreasing smoothly on cooling.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

If pressure suppresses the ordering by weakening correlations rather than by changing the band topology, then the flat Ni-$d_{3z^{2}-r^{2}}$ band should reappear at the Fermi level in the pressurized $Fmmm$ phase, which is directly checkable by pressure-dependent ARPES or by optical spectroscopy in a diamond anvil cell.
The orbital-selective reading predicts that anything which shifts the flat band away from $E_F$ at ambient pressure, such as doping or strain, should move $T^{ast}$ and the D2 weight together; a material where $T^{ast}$ survives but D2 persists would count against the assignment.
The two-Drude decomposition used here should transfer directly to the trilayer La4Ni3O10, which shows a similar transition near 140 K, and comparing the D2 weight in the two would test whether the same flat band is responsible in both.
The $2Delta/k_BT^{ast} pprox 10$ ratio puts the ordering in the short-coherence-length regime, so one would expect a substantial fluctuation regime above $T^{ast}$ visible in NMR relaxation or in the excess low-frequency conductivity, a prediction this optical data set does not itself test.

Original abstract

The discovery of superconductivity with a critical temperature of about 80~K in La$_{3}$Ni$_{2}$O$_{7}$ single crystals under pressure has received enormous attention. La$_{3}$Ni$_{2}$O$_{7}$ is not superconducting under ambient pressure but exhibits a transition at $T^{\ast} \simeq 115$~K. Understanding the electronic correlations and charge dynamics is an important step towards the origin of superconductivity and other instabilities. Here, our optical study shows that La$_{3}$Ni$_{2}$O$_{7}$ features strong electronic correlations which significantly reduce the electron's kinetic energy and place this system in the proximity of the Mott phase. The low-frequency optical conductivity reveals two Drude components arising from multiple bands at the Fermi level. The transition at $T^{\ast}$ removes the Drude component exhibiting non-Fermi liquid behavior, whereas the one with Fermi-liquid behavior is barely affected. These observations in combination with theoretical results suggest that the Fermi surface dominated by the Ni-$d_{3z^{2}-r^{2}}$ orbital is removed due to the transition at $T^{\ast}$. Our experimental results provide pivotal information for understanding the transition at $T^{\ast}$ and superconductivity in La$_{3}$Ni$_{2}$O$_{7}$.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 6,446 input tokens.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.07 · human participants 0.02 · controlled comparison 0.11 · randomized assignment 0.01 · states quantitative result 0.92 · compares with prior results 0.18 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v3. Results and the main claim are underlined; show every role.

The discovery of superconductivity with a critical temperature of about 80~K in La$_{3}$Ni$_{2}$O$_{7}$ single crystals under pressure has received enormous attention. La$_{3}$Ni$_{2}$O$_{7}$ is not superconducting under ambient pressure but exhibits a transition at $T^{\ast} \simeq 115$~K. Understanding the electronic correlations and charge dynamics is an important step towards the origin of superconductivity and other instabilities. Here, our optical study shows that La$_{3}$Ni$_{2}$O$_{7}$ features strong electronic correlations which significantly reduce the electron's kinetic energy and place this system in the proximity of the Mott phase. The low-frequency optical conductivity reveals two Drude components arising from multiple bands at the Fermi level. The transition at $T^{\ast}$ removes the Drude component exhibiting non-Fermi liquid behavior, whereas the one with Fermi-liquid behavior is barely affected. These observations in combination with theoretical results suggest that the Fermi surface dominated by the Ni-$d_{3z^{2}-r^{2}}$ orbital is removed due to the transition at $T^{\ast}$. Our experimental results provide pivotal information for understanding the transition at $T^{\ast}$ and superconductivity in La$_{3}$Ni$_{2}$O$_{7}$.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	The discovery of superconductivity with a critical temperature of about 80~K in La$_{3}$Ni$_{2}$O$_{7}$ single crystals under pressure has received enormous attention.	background 1.00	0.04	0.02	asserted 1.00
s1	La$_{3}$Ni$_{2}$O$_{7}$ is not superconducting under ambient pressure but exhibits a transition at $T^{\ast} \simeq 115$~K.	background 0.99	0.20	0.03	asserted 1.00
s2	Understanding the electronic correlations and charge dynamics is an important step towards the origin of superconductivity and other instabilities.	background 0.82	0.05	0.04	asserted 0.98
s3	Here, our optical study shows that La$_{3}$Ni$_{2}$O$_{7}$ features strong electronic correlations which significantly reduce the electron's kinetic energy and place this system in the proximity of the Mott phase.	result 0.95	0.94	0.35	asserted 1.00
s4	The low-frequency optical conductivity reveals two Drude components arising from multiple bands at the Fermi level.	result 1.00	0.93	0.05	asserted 1.00
s5	The transition at $T^{\ast}$ removes the Drude component exhibiting non-Fermi liquid behavior, whereas the one with Fermi-liquid behavior is barely affected.	result 1.00	0.93	0.15	asserted 1.00
s6	These observations in combination with theoretical results suggest that the Fermi surface dominated by the Ni-$d_{3z^{2}-r^{2}}$ orbital is removed due to the transition at $T^{\ast}$.	interpretation 1.00	0.53	0.54	hedged possibility 0.99
s7	Our experimental results provide pivotal information for understanding the transition at $T^{\ast}$ and superconductivity in La$_{3}$Ni$_{2}$O$_{7}$.	interpretation 0.72	0.76	0.14	asserted 0.99

What kind of paper the classifier reports this is: empirical study 1.00 · evidence from observation or experiment 1.00.

What was examined, and what was not

sources read

arXiv listing abstract v3

not examined

full text
figures and tables
references and citing sentences
relations to other papers

levels run

P abstract

not run

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T body sentences
C citations
R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures

**Figure 1.** Reflectivity and optical conductivity of La3Ni2O7. a The temperaturedependent resistivity ρ(T) obtained from transport measurements (red solid curve) and that from optical measurements (blue open circles). b The far-infrared ab-plane reflectivity R(ω) of La3Ni2O7 at different temperatures. The spectra below 125 K are shifted down by 0.5 to show the temperature dependence more clearly. c The optical conductivity σ1(ω) of La3Ni2O7 at different temperatures in the far-infrared range. The curves below 125 K are shifted down by 1250 Ω −1cm−1 . The inset shows an enlarge view of σ1(ω)…

**Figure 2.** Drude-Lorentz fit and theoretical calculations. a The measured σ1(ω) of La3Ni2O7 at 150 K (cyan solid curve) and the Drude-Lorentz fitting result (black dashed line). The fitting curve is decomposed into two Drude components (red and blue shaded areas) and a series of Lorentz components L1 (green hatched area), L2 (orange hatched area), L3 (cyan hatched area), L4 (purple hatched area) and LH (grey hatched area). The inset shows an enlarged view of the fitting result in the low-frequency range. b The calculated electronic band structure for La3Ni2O7. c The calculated σ1(ω) of…

**Figure 3.** Temperature dependence of the Drude parameters. The temperature dependence of the weight for D1 (a) and D2 (b). c The quasiparticle scattering rate for D1 as a function of temperature. The solid line denotes a quadratic temperature dependence. d The temperature dependence of the quasiparticle scattering rate for D2. The dashed line is a linear fit. 28

**Figure 4.** Energy scale of the gap and spectral weight redistribution. a The frequency-dependent spectral weight ratio S(200 K)/S(300 K) (red curve) and S(5 K)/S(125 K) (blue curve). b The difference optical conductivity ∆σ1(ω) at 5 K. The arrow indicates the zero-crossing point in ∆σ1(ω) which corresponds to the gap energy 2∆. c–e The evolution of the spectral weight as a function of temperature for cutoff frequencies ωc = 600 cm−1 , ωc = 1000 cm−1 and ωc = 6500 cm−1 . f The evolution of ∆ with temperature (red open circles). The blue solid line denotes the mean-field behavior. 29

Figures reproduced from arXiv:2307.02950 by the authors.

References

Works cited (68)

[32]

Qazilbash, M. M. et al. Electronic correlations in the iron pnictides. Nat. Phys. 5, 647–650 (2009). 18

View on Pith 2009
[42]

Y ang, J. et al. Orbital-Dependent Electron Correlation in Double-Layer N ickelate La3Ni2O7. arXiv (2023). arXiv:2309.01148

View on Pith Pith review arXiv 2023
[1]

Li, D. et al. Superconductivity in an inﬁnite-layer nickelate. Nature 572, 624–627 (2019)

View on Pith 2019
[2]

Li, D. et al. Superconducting Dome in Nd1−xSrxNiO2 Inﬁnite Layer Films. Phys. Rev. Lett. 125, 027001 (2020)

View on Pith 2020
[3]

Zeng, S. et al. Phase Diagram and Superconducting Dome of Inﬁnite-Layer Nd1−xSrxNiO2 Thin Films. Phys. Rev. Lett. 125, 147003 (2020)

View on Pith 2020
[4]

Osada, M. et al. A Superconducting Praseodymium Nickelate with Inﬁnite Lay er Structure. Nano Lett. 20, 5735–5740 (2020)

View on Pith 2020
[5]

Osada, M. et al. Nickelate Superconductivity without Rare-Earth Magnetis m: (La,Sr)NiO 2. Adv. Mater .33, 2104083 (2021)

View on Pith 2021
[6]

Wang, N. N. et al. Pressure-induced monotonic enhancement of Tc to over 30 K in supercon- ducting Pr0.82Sr0.18NiO2 thin ﬁlms. Nat. Commun. 13, 4367– (2022). 15

View on Pith 2022
[7]

Sun, W. et al. Evidence for Anisotropic Superconductivity Beyond Pauli L imit in Inﬁnite- Layer Lanthanum Nickelates. Adv. Mater .n/a, 2303400 (2023)

View on Pith 2023
[8]

Zeng, S. et al. Superconductivity in inﬁnite-layer nickelate La 1−xCaxNiO2 thin ﬁlms. Sci. Adv. 8, eabl9927 (2022)

View on Pith 2022
[9]

Pan, G. A. et al. Superconductivity in a quintuple-layer square-planar nic kelate. Nat. Mater . 21, 160–164 (2022)

View on Pith 2022
[10]

Li, Q. et al. Absence of superconductivity in bulk Nd 1−xSrxNiO2. Commun. Mater . 1, 16 (2020)

View on Pith 2020
[11]

Wang, B.-X. et al. Synthesis and characterization of bulk Nd1−xSrxNiO2 and Nd1−xSrxNiO3. Phys. Rev. Materials 4, 084409 (2020)

View on Pith 2020
[12]

Sun, H. et al. Signatures of superconductivity near 80 K in a nickelate und er high pressure. Nature 621, 493 (2023)

View on Pith 2023
[13]

Hou, J. et al. Emergence of high-temperature superconducting phase in th e pressurized La3Ni2O7 crystals. arXiv (2023). arXiv:2307.09865

View on Pith Pith review arXiv 2023
[14]

Zhang, Y . et al. High-temperature superconductivity with zero-resistanc e and strange metal behavior in La 3Ni2O7. arXiv (2023). arXiv:2307.14819

View on Pith Pith review arXiv 2023
[15]

Wang, G. et al. Pressure-Induced Superconductivity In Polycrystalline La3Ni2O7−δ. Phys. Rev. X 14, 011040 (2024). 16

View on Pith 2024
[16]

Luo, Z., Hu, X., Wang, M., W´ u, W. & Y ao, D.-X. Bilayer Two- Orbital Model of La3Ni2O7 under Pressure. Phys. Rev. Lett. 131, 126001 (2023)

View on Pith 2023
[17]

Zhang, Y ., Lin, L.-F., Moreo, A. & Dagotto, E. Electronic structure, dimer physics, orbital- selective behavior, and magnetic tendencies in the bilayer nickelate superconductor La3Ni2O7 under pressure. Phys. Rev. B 108, L180510 (2023)

View on Pith 2023
[18]

Y ang, Q.-G., Liu, H.-Y ., Wang, D. & Wang, Q.-H. Possible S ±-wave superconductivity in La3Ni2O7. arXiv (2023). arXiv:2306.03706

View on Pith Pith review arXiv 2023
[19]

Lechermann, F., Gondolf, J., B¨ otzel, S. & Eremin, I. M. E lectronic correlations and supercon- ducting instability in La 3Ni2O7 under high pressure. arXiv (2023). arXiv:2306.05121

View on Pith Pith review arXiv 2023
[20]

Gu, Y ., Le, C., Y ang, Z., Wu, X. & Hu, J. Effective model and pairing tendency in bilayer Ni-based superconductor La 3Ni2O7. arXiv (2023). arXiv:2306.07275

View on Pith Pith review arXiv 2023
[21]

Shen, Y ., Qin, M. & Zhang, G.-M. Effective bi-layer model Hamiltonian and density-matrix renormalization group study for the high- Tc superconductivity in La 3Ni2O7 under high pres- sure. arXiv (2023). arXiv:2306.07837

View on Pith Pith review arXiv 2023
[22]

Sakakibara, H., Kitamine, N., Ochi, M. & Kuroki, K. Possi ble high Tc superconductivity in La3Ni2O7 under high pressure through manifestation of a nearly-half -ﬁlled bilayer Hubbard model. arXiv (2023). arXiv:2306.06039

View on Pith Pith review arXiv 2023
[23]

Shilenko, D. A. & Leonov, I. V . Correlated electronic str ucture, orbital-selective behav- ior, and magnetic correlations in double-layer La 3Ni2O7 under pressure. arXiv (2023). arXiv:2306.14841. 17

View on Pith Pith review arXiv 2023
[24]

Christiansson, V ., Petocchi, F. & Werner, P . Correlatedelectronic structure of La 3Ni2O7 under pressure. arXiv (2023). arXiv:2306.07931

View on Pith Pith review arXiv 2023
[25]

Taniguchi, S. et al. Transport, Magnetic and Thermal Properties of La 3Ni2O7−δ. J. Phys. Soc. Jpn. 64, 1644–1650 (1995)

View on Pith 1995
[26]

Kobayashi, Y . et al. Transport and Magnetic Properties of La 3Ni2O7−δ and La 4Ni3O10−δ. J. Phys. Soc. Jpn. 65, 3978–3982 (1996)

View on Pith 1996
[27]

Wu, G., Neumeier, J. J. & Hundley, M. F. Magnetic suscepti bility, heat capacity, and pressure dependence of the electrical resistivity of La 3Ni2O7 and La4Ni3O10. Phys. Rev. B 63, 245120 (2001)

View on Pith 2001
[28]

Liu, Z. et al. Evidence for charge and spin density waves in single crystal s of La 3Ni2O7 and La3Ni2O6. Sci. China Phys. Mech. Astron. 66, 217411 (2023)

View on Pith 2023
[29]

Seo, D.-K., Liang, W., Whangbo, M.-H., Zhang, Z. & Greenb latt, M. Electronic Band Struc- ture and Madelung Potential Study of the Nickelates La 2NiO4, La 3Ni2O7, and La 4Ni3O10. Inorg. Chem. 35, 6396–6400 (1996)

View on Pith 1996
[30]

Nakata, M., Ogura, D., Usui, H. & Kuroki, K. Finite-energ y spin ﬂuctuations as a pairing glue in systems with coexisting electron and hole bands. Phys. Rev. B 95, 214509 (2017)

View on Pith 2017
[31]

Si, Q. Electrons on the verge. Nat. Phys. 5, 629–630 (2009)

View on Pith 2009
[33]

Geisler, B. et al. Optical properties and electronic correlations in La 3Ni2O7−δ bilayer nicke- lates under high pressure. arXiv (2024). arXiv:2401.04258

View on Pith Pith review arXiv 2024
[34]

Millis, A. J., Zimmers, A., Lobo, R. P . S. M., Bontemps, N. & Homes, C. C. Mott physics and the optical conductivity of electron-doped cuprates. Phys. Rev. B 72, 224517 (2005)

View on Pith 2005
[35]

Schafgans, A. A. et al. Electronic Correlations and Unconventional Spectral Weig ht Trans- fer in the High-Temperature Pnictide BaFe 2−xCoxAs2 Superconductor Using Infrared Spec- troscopy. Phys. Rev. Lett. 108, 147002 (2012)

View on Pith 2012
[36]

Xu, Y . et al. Electronic correlations and ﬂattened band in magnetic Weyl semimetal candidate Co3Sn2S2. Nat. Commun. 11, 3985 (2020)

View on Pith 2020
[37]

Degiorgi, L. Electronic correlations in iron-pnictide superconductors and beyond: lessons learned from optics. New J. Phys. 13, 023011 (2011)

View on Pith 2011
[38]

Shao, Y . et al. Electronic correlations in nodal-line semimetals. Nat. Phys. 16, 636–641 (2020)

View on Pith 2020
[39]

Kotliar, G. & V ollhardt, D. Strongly Correlated Materia ls: Insights From Dynamical Mean- Field Theory. Physics Today 57, 53–59 (2004)

View on Pith 2004
[40]

Basov, D. N., Averitt, R. D., van der Marel, D., Dressel, M . & Haule, K. Electrodynamics of correlated electron materials. Rev. Mod. Phys. 83, 471–542 (2011)

View on Pith 2011
[41]

Imada, M., Fujimori, A. & Tokura, Y . Metal-insulator tra nsitions. Rev. Mod. Phys. 70, 1039– 1263 (1998). 19

View on Pith 1998
[43]

Keimer, B., Kivelson, S. A., Norman, M. R., Uchida, S. & Za anen, J. From quantum matter to high-temperature superconductivity in copper oxides. Nature 518, 179–186 (2015)

View on Pith 2015
[44]

Hu, W. Z. et al. Origin of the Spin Density Wave Instability in AFe2As2 (A = Ba, Sr) as Revealed by Optical Spectroscopy. Phys. Rev. Lett. 101, 257005 (2008)

View on Pith 2008
[45]

Zhou, X. et al. Origin of charge density wave in the kagome metal CsV3Sb5 as revealed by optical spectroscopy. Phys. Rev. B 104, L041101 (2021)

View on Pith 2021
[46]

Homes, C. C. et al. Determination of the optical properties of La 2−xBaxCuO4 for several dopings, including the anomalous x = 18 phase. Phys. Rev. B 85, 134510 (2012)

View on Pith 2012
[47]

Tediosi, R. et al. Evidence for strongly coupled charge-density-wave orderi ng in three- dimensional R5Ir4Si10 compounds from optical measurements. Phys. Rev. B 80, 035107 (2009)

View on Pith 2009
[48]

Chen, X., Jiang, P ., Li, J., Zhong, Z. & Lu, Y . Critical cha rge and spin instabilities in super- conducting La3Ni2O7. arXiv (2023). arXiv.2307.07154

View on Pith Pith review arXiv 2023
[49]

Zhang, J. et al. Intertwined density waves in a metallic nickelate. Nat. Commun. 11, 6003– (2020)

View on Pith 2020
[50]

Li, H. et al. Fermiology and electron dynamics of trilayer nickelate La 4Ni3O10. Nat. Commun. 8, 704– (2017). 20

View on Pith 2017
[51]

Uykur, E., Ortiz, B. R., Wilson, S. D., Dressel, M. & Tsirl in, A. A. Optical detection of the density-wave instability in the kagome metal KV 3Sb5. npj Quantum Mater .7, 16 (2022)

View on Pith 2022
[52]

Zhou, X. et al. Effects of niobium doping on the charge density wave and elec tronic correla- tions in the kagome metal Cs (V1−xNbx)3Sb5. Phys. Rev. B 107, 125124 (2023)

View on Pith 2023
[53]

Zhou, X. et al. Electronic correlations and evolution of the charge densit y wave in the kagome metals AV3Sb5 (A = K, Rb, Cs). Phys. Rev. B 107, 165123 (2023)

View on Pith 2023
[54]

Peierls, R. E. Quantum Theory of Solids (Clarendon, Oxford, 1955)

View on Pith 1955
[55]

Fr¨ ohlich, H. On the theory of superconductivity: the on e-dimensional case. Proc. R. Soc. Lond. A 223, 296 (1954)

View on Pith 1954
[56]

Gr¨ uner, G. The dynamics of charge-density waves. Rev. Mod. Phys. 60, 1129–1181 (1988)

View on Pith 1988
[57]

Gr¨ uner, G. The dynamics of spin-density waves. Rev. Mod. Phys. 66, 1–24 (1994)

View on Pith 1994
[58]

McMillan, W. L. Microscopic model of charge-density wav es in 2 H-TaSe2. Phys. Rev. B 16, 643–650 (1977)

View on Pith 1977
[59]

LaBollita, H., Pardo, V ., Norman, M. R. & Botana, A. S. Ele ctronic structure and magnetic properties of La 3Ni2O7 under pressure. arXiv (2023). arXiv:2309.17279

View on Pith Pith review arXiv 2023
[60]

Xu, B. et al. Optical spectroscopy of the Weyl semimetal TaAs. Phys. Rev. B 93, 121110 (2016)

View on Pith 2016
[61]

Wang, Y ., Kang, C.-J., Miao, H. & Kotliar, G. Hund’s metalphysics: From SrNiO2 to LaNiO2. Phys. Rev. B 102, 161118 (2020). 21

View on Pith 2020
[62]

Kang, C.-J. & Kotliar, G. Optical Properties of the Inﬁni te-Layer La1−xSrxNiO2 and Hidden Hund’s Physics. Phys. Rev. Lett. 126, 127401 (2021)

View on Pith 2021
[63]

Homes, C. C., Reedyk, M., Cradles, D. A. & Timusk, T. Techn ique for measuring the re- ﬂectance of irregular, submillimeter-sized samples. Appl. Opt. 32, 2976–2983 (1993)

View on Pith 1993
[64]

Dressel, M. & Gr¨ uner, G. Electrodynamics of Solids (Cambridge University press, 2002)

View on Pith 2002
[65]

Tanner, D. B. Optical Effeccts in Solids (Cambridge University press, 2019)

View on Pith 2019
[66]

Blaha, P ., Schwarz, K., Madsen, G. K. H., Kvasnicka, D. & L uitz, J. WIEN2K, An Augmented Plane Wave + Local Orbitals Program for Calculating Crystal Properties (Technische Uni- versit¨ at Wien, Vienna, Austria, 2001)

View on Pith 2001
[67]

Perdew, J. P ., Burke, K. & Ernzerhof, M. Generalized Grad ient Approximation Made Simple. Phys. Rev. Lett. 77, 3865–3868 (1996)

View on Pith 1996
[68]

Ling, C. D., Argyriou, D. N., Wu, G. & Neumeier, J. Neutron Diffraction Study of La 3Ni2O7: Structural Relationships Among n = 1, 2, and 3 Phases La n+1NinO3n+1. J. Solid State Chem. 152, 517–525 (2000). Methods Single crystal growth. High-quality single crystals of La 3Ni2O7 were grown by a vertical optical- image ﬂoating zone furnace with an oxygen pres...

View on Pith 2000

Forward citations

Cited by 2 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

High-temperature superconductivity with zero-resistance and strange metal behavior in La$_{3}$Ni$_{2}$O$_{7-\delta}$
cond-mat.supr-con 2023-07 conditional novelty 6.0 of 10

Under hydrostatic pressure, single crystals of La3Ni2O7-δ show zero electrical resistance below about 40 K, confirming bulk high-temperature superconductivity in a nickelate.
Superconductivity from Doping Symmetric Mass Generation Insulators: Application to La$_3$Ni$_2$O$_7$ under Pressure
cond-mat.str-el 2023-08 conditional novelty 5.0 of 10

Doping a featureless Mott insulator in a bilayer square-lattice model yields s-wave interlayer superconductivity with a BCS-BEC crossover, proposed as the mechanism for La3Ni2O7 under pressure.

How the literature uses it

43 arXiv papers cite this in 71 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 45 sentences without a confident label

Uses its data or values 1 paper

When pressure is applied, the crystal structure of La3Ni2O7 undergoes a phase transition from the orthorhombic symmetry $Amam$ to $Fmmm$ at approximately 14 GPa, where superconductivity emerges [ref] .

Superconductivity in nickelate and cuprate superconductors with strong bilayer coupling · Introduction · 0.82

Compares with it 4 papers

We begin with a detailed analysis of the in-plane optical conductivity $σ_xx,yy(ω)$ of La$_3$Ni$_2$O$_7$ at ambient pressure [Fig. [ref](a); $Cmcm$ space group] and close comparison with recently measured data obtained from reflectivity experiments [ref] .

Optical properties and electronic correlations in La$_3$Ni$_2$O$_7$ bilayer nickelates under high pressure · Optical spectrum, dipole transition analysis, and impact of oxygen vacancies · 0.97
[ref](d)], consistent with experimental results [ref] .

Antiferromagnetic Ground State, Charge Density Waves and Oxygen Vacancies Induced Metal-Insulator Transition in Pressurized La$_{3}$Ni$_{2}$O$_{7}$ · Introduction · 0.91
Similar values have been previously reported for the optical conductivity of La327 ($Δ∼100$ meV) [ref] and ARPES for La4310 ($Δ∼40$ meV).

Multiband Metallic Ground State in Multilayered Nickelates La$_3$Ni$_2$O$_7$ and La$_4$Ni$_3$O$_{10}$ Probed by $^{139}$La-NMR at Ambient Pressure · Introduction · 0.87

Cites it as support 4 papers

This is confirmed in Monte Carlo simulations of the minimal model [ref] , in good accordance with experimental observations [ref] .

Inter-layer valence bonds and two-component theory for high-$T_c$ superconductivity of La$_{3}$Ni$_{2}$O$_{7}$ under pressure · Introduction · 0.96
The possibility of Mott physics with strong renormalization has been confirmed in latest optical measurements at ambient pressure [ref] .

Flat bands promoted by Hund's rule coupling in the candidate double-layer high-temperature superconductor La$_3$Ni$_2$O$_7$ · Introduction · 0.99
Such a viewpoint is supported by a recent experiment [ref] which revealed that the LNO system is near the boundary of the Mott transition.

Interlayer Coupling Driven High-Temperature Superconductivity in La$_3$Ni$_2$O$_7$ Under Pressure · Introduction · 0.96

Cites it as background 17 papers

The recently discovered high-$T_c$ superconductivity in the bilayer nickelate La$_3$Ni$_2$O$_7$ under high pressure [ref] has stimulated intensive interest concerning its basic electronic structures [ref] and possible pairing mechanism [ref] .

High-$T_c$ superconductivity by mobilizing local spin singlets and possible route to higher $T_c$ in pressurized La$_3$Ni$_2$O$_7$ · Introduction · 0.99
The recent discovered high-temperature superconductivity in La$_3$Ni$_2$O$_7$ (LNO) [ref] has attracted great interests both experimentally [ref] and theoretically [ref] .

Effect of Rare-earth Element Substitution in Superconducting R$_3$Ni$_2$O$_7$ Under Pressure · Introduction · 0.94
The recent observation of superconductivity with $T_c ∼80$ K in pressurized La$_3$Ni$_2$O$_7$ [ref] suggested the bilayer Ruddlesden-Popper compounds as an intriguing new member of the steadily growing family of superconducting nickelates [ref] and instantly sparked considerable interest [ref] .

Optical properties and electronic correlations in La$_3$Ni$_2$O$_7$ bilayer nickelates under high pressure · Introduction · 0.96

What it cites · 28 sentences without a confident label

Uses data or values from 1 paper

ARPES data at 18 K has shown that while the Ni-$d_x^2 - y^2$ derived bands ($α$ and $β$) cross , the Ni-$d_3z^2 - r^2$ derived band ($γ$) is below [ref] .

Orbital-Dependent Electron Correlation in Double-Layer Nickelate La3Ni2O7 · Discussion · 0.81

Cites as support 2 papers

Theoretical work [ref] has revealed remarkable orbital differentiation in with the Ni-$d_3z^2 - r^2$ orbital being more strongly correlated, thus inducing spin fluctuations and non-Fermi liquid behavior.

Electronic correlations and superconducting instability in La$_3$Ni$_2$O$_7$ under high pressure · Discussion · 1.00
Theoretical work [ref] has revealed remarkable orbital differentiation in with the Ni-$d_3z^2 - r^2$ orbital being more strongly correlated, thus inducing spin fluctuations and non-Fermi liquid behavior.

Correlated electronic structure, orbital-selective behavior, and magnetic correlations in double-layer La$_3$Ni$_2$O$_7$ under pressure · Discussion · 1.00

Discussion

Disagree with the review, or know something it missed? Leave a comment, highlight any passage above to comment on it, or challenge this review formally.

[1] [32]

Qazilbash, M. M. et al. Electronic correlations in the iron pnictides. Nat. Phys. 5, 647–650 (2009). 18

View on Pith 2009

[2] [42]

Y ang, J. et al. Orbital-Dependent Electron Correlation in Double-Layer N ickelate La3Ni2O7. arXiv (2023). arXiv:2309.01148

View on Pith Pith review arXiv 2023

[3] [1]

Li, D. et al. Superconductivity in an inﬁnite-layer nickelate. Nature 572, 624–627 (2019)

View on Pith 2019

[4] [2]

Li, D. et al. Superconducting Dome in Nd1−xSrxNiO2 Inﬁnite Layer Films. Phys. Rev. Lett. 125, 027001 (2020)

View on Pith 2020

[5] [3]

Zeng, S. et al. Phase Diagram and Superconducting Dome of Inﬁnite-Layer Nd1−xSrxNiO2 Thin Films. Phys. Rev. Lett. 125, 147003 (2020)

View on Pith 2020

[6] [4]

Osada, M. et al. A Superconducting Praseodymium Nickelate with Inﬁnite Lay er Structure. Nano Lett. 20, 5735–5740 (2020)

View on Pith 2020

[7] [5]

Osada, M. et al. Nickelate Superconductivity without Rare-Earth Magnetis m: (La,Sr)NiO 2. Adv. Mater .33, 2104083 (2021)

View on Pith 2021

[8] [6]

Wang, N. N. et al. Pressure-induced monotonic enhancement of Tc to over 30 K in supercon- ducting Pr0.82Sr0.18NiO2 thin ﬁlms. Nat. Commun. 13, 4367– (2022). 15

View on Pith 2022

[9] [7]

Sun, W. et al. Evidence for Anisotropic Superconductivity Beyond Pauli L imit in Inﬁnite- Layer Lanthanum Nickelates. Adv. Mater .n/a, 2303400 (2023)

View on Pith 2023

[10] [8]

Zeng, S. et al. Superconductivity in inﬁnite-layer nickelate La 1−xCaxNiO2 thin ﬁlms. Sci. Adv. 8, eabl9927 (2022)

View on Pith 2022

[11] [9]

Pan, G. A. et al. Superconductivity in a quintuple-layer square-planar nic kelate. Nat. Mater . 21, 160–164 (2022)

View on Pith 2022

[12] [10]

Li, Q. et al. Absence of superconductivity in bulk Nd 1−xSrxNiO2. Commun. Mater . 1, 16 (2020)

View on Pith 2020

[13] [11]

Wang, B.-X. et al. Synthesis and characterization of bulk Nd1−xSrxNiO2 and Nd1−xSrxNiO3. Phys. Rev. Materials 4, 084409 (2020)

View on Pith 2020

[14] [12]

Sun, H. et al. Signatures of superconductivity near 80 K in a nickelate und er high pressure. Nature 621, 493 (2023)

View on Pith 2023

[15] [13]

Hou, J. et al. Emergence of high-temperature superconducting phase in th e pressurized La3Ni2O7 crystals. arXiv (2023). arXiv:2307.09865

View on Pith Pith review arXiv 2023

[16] [14]

Zhang, Y . et al. High-temperature superconductivity with zero-resistanc e and strange metal behavior in La 3Ni2O7. arXiv (2023). arXiv:2307.14819

View on Pith Pith review arXiv 2023

[17] [15]

Wang, G. et al. Pressure-Induced Superconductivity In Polycrystalline La3Ni2O7−δ. Phys. Rev. X 14, 011040 (2024). 16

View on Pith 2024

[18] [16]

Luo, Z., Hu, X., Wang, M., W´ u, W. & Y ao, D.-X. Bilayer Two- Orbital Model of La3Ni2O7 under Pressure. Phys. Rev. Lett. 131, 126001 (2023)

View on Pith 2023

[19] [17]

Zhang, Y ., Lin, L.-F., Moreo, A. & Dagotto, E. Electronic structure, dimer physics, orbital- selective behavior, and magnetic tendencies in the bilayer nickelate superconductor La3Ni2O7 under pressure. Phys. Rev. B 108, L180510 (2023)

View on Pith 2023

[20] [18]

Y ang, Q.-G., Liu, H.-Y ., Wang, D. & Wang, Q.-H. Possible S ±-wave superconductivity in La3Ni2O7. arXiv (2023). arXiv:2306.03706

View on Pith Pith review arXiv 2023

[21] [19]

Lechermann, F., Gondolf, J., B¨ otzel, S. & Eremin, I. M. E lectronic correlations and supercon- ducting instability in La 3Ni2O7 under high pressure. arXiv (2023). arXiv:2306.05121

View on Pith Pith review arXiv 2023

[22] [20]

Gu, Y ., Le, C., Y ang, Z., Wu, X. & Hu, J. Effective model and pairing tendency in bilayer Ni-based superconductor La 3Ni2O7. arXiv (2023). arXiv:2306.07275

View on Pith Pith review arXiv 2023

[23] [21]

Shen, Y ., Qin, M. & Zhang, G.-M. Effective bi-layer model Hamiltonian and density-matrix renormalization group study for the high- Tc superconductivity in La 3Ni2O7 under high pres- sure. arXiv (2023). arXiv:2306.07837

View on Pith Pith review arXiv 2023

[24] [22]

Sakakibara, H., Kitamine, N., Ochi, M. & Kuroki, K. Possi ble high Tc superconductivity in La3Ni2O7 under high pressure through manifestation of a nearly-half -ﬁlled bilayer Hubbard model. arXiv (2023). arXiv:2306.06039

View on Pith Pith review arXiv 2023

[25] [23]

Shilenko, D. A. & Leonov, I. V . Correlated electronic str ucture, orbital-selective behav- ior, and magnetic correlations in double-layer La 3Ni2O7 under pressure. arXiv (2023). arXiv:2306.14841. 17

View on Pith Pith review arXiv 2023

[26] [24]

Christiansson, V ., Petocchi, F. & Werner, P . Correlatedelectronic structure of La 3Ni2O7 under pressure. arXiv (2023). arXiv:2306.07931

View on Pith Pith review arXiv 2023

[27] [25]

Taniguchi, S. et al. Transport, Magnetic and Thermal Properties of La 3Ni2O7−δ. J. Phys. Soc. Jpn. 64, 1644–1650 (1995)

View on Pith 1995

[28] [26]

Kobayashi, Y . et al. Transport and Magnetic Properties of La 3Ni2O7−δ and La 4Ni3O10−δ. J. Phys. Soc. Jpn. 65, 3978–3982 (1996)

View on Pith 1996

[29] [27]

Wu, G., Neumeier, J. J. & Hundley, M. F. Magnetic suscepti bility, heat capacity, and pressure dependence of the electrical resistivity of La 3Ni2O7 and La4Ni3O10. Phys. Rev. B 63, 245120 (2001)

View on Pith 2001

[30] [28]

Liu, Z. et al. Evidence for charge and spin density waves in single crystal s of La 3Ni2O7 and La3Ni2O6. Sci. China Phys. Mech. Astron. 66, 217411 (2023)

View on Pith 2023

[31] [29]

Seo, D.-K., Liang, W., Whangbo, M.-H., Zhang, Z. & Greenb latt, M. Electronic Band Struc- ture and Madelung Potential Study of the Nickelates La 2NiO4, La 3Ni2O7, and La 4Ni3O10. Inorg. Chem. 35, 6396–6400 (1996)

View on Pith 1996

[32] [30]

Nakata, M., Ogura, D., Usui, H. & Kuroki, K. Finite-energ y spin ﬂuctuations as a pairing glue in systems with coexisting electron and hole bands. Phys. Rev. B 95, 214509 (2017)

View on Pith 2017

[33] [31]

Si, Q. Electrons on the verge. Nat. Phys. 5, 629–630 (2009)

View on Pith 2009

[34] [33]

Geisler, B. et al. Optical properties and electronic correlations in La 3Ni2O7−δ bilayer nicke- lates under high pressure. arXiv (2024). arXiv:2401.04258

View on Pith Pith review arXiv 2024

[35] [34]

Millis, A. J., Zimmers, A., Lobo, R. P . S. M., Bontemps, N. & Homes, C. C. Mott physics and the optical conductivity of electron-doped cuprates. Phys. Rev. B 72, 224517 (2005)

View on Pith 2005

[36] [35]

Schafgans, A. A. et al. Electronic Correlations and Unconventional Spectral Weig ht Trans- fer in the High-Temperature Pnictide BaFe 2−xCoxAs2 Superconductor Using Infrared Spec- troscopy. Phys. Rev. Lett. 108, 147002 (2012)

View on Pith 2012

[37] [36]

Xu, Y . et al. Electronic correlations and ﬂattened band in magnetic Weyl semimetal candidate Co3Sn2S2. Nat. Commun. 11, 3985 (2020)

View on Pith 2020

[38] [37]

Degiorgi, L. Electronic correlations in iron-pnictide superconductors and beyond: lessons learned from optics. New J. Phys. 13, 023011 (2011)

View on Pith 2011

[39] [38]

Shao, Y . et al. Electronic correlations in nodal-line semimetals. Nat. Phys. 16, 636–641 (2020)

View on Pith 2020

[40] [39]

Kotliar, G. & V ollhardt, D. Strongly Correlated Materia ls: Insights From Dynamical Mean- Field Theory. Physics Today 57, 53–59 (2004)

View on Pith 2004

[41] [40]

Basov, D. N., Averitt, R. D., van der Marel, D., Dressel, M . & Haule, K. Electrodynamics of correlated electron materials. Rev. Mod. Phys. 83, 471–542 (2011)

View on Pith 2011

[42] [41]

Imada, M., Fujimori, A. & Tokura, Y . Metal-insulator tra nsitions. Rev. Mod. Phys. 70, 1039– 1263 (1998). 19

View on Pith 1998

[43] [43]

Keimer, B., Kivelson, S. A., Norman, M. R., Uchida, S. & Za anen, J. From quantum matter to high-temperature superconductivity in copper oxides. Nature 518, 179–186 (2015)

View on Pith 2015

[44] [44]

Hu, W. Z. et al. Origin of the Spin Density Wave Instability in AFe2As2 (A = Ba, Sr) as Revealed by Optical Spectroscopy. Phys. Rev. Lett. 101, 257005 (2008)

View on Pith 2008

[45] [45]

Zhou, X. et al. Origin of charge density wave in the kagome metal CsV3Sb5 as revealed by optical spectroscopy. Phys. Rev. B 104, L041101 (2021)

View on Pith 2021

[46] [46]

Homes, C. C. et al. Determination of the optical properties of La 2−xBaxCuO4 for several dopings, including the anomalous x = 18 phase. Phys. Rev. B 85, 134510 (2012)

View on Pith 2012

[47] [47]

Tediosi, R. et al. Evidence for strongly coupled charge-density-wave orderi ng in three- dimensional R5Ir4Si10 compounds from optical measurements. Phys. Rev. B 80, 035107 (2009)

View on Pith 2009

[48] [48]

Chen, X., Jiang, P ., Li, J., Zhong, Z. & Lu, Y . Critical cha rge and spin instabilities in super- conducting La3Ni2O7. arXiv (2023). arXiv.2307.07154

View on Pith Pith review arXiv 2023

[49] [49]

Zhang, J. et al. Intertwined density waves in a metallic nickelate. Nat. Commun. 11, 6003– (2020)

View on Pith 2020

[50] [50]

Li, H. et al. Fermiology and electron dynamics of trilayer nickelate La 4Ni3O10. Nat. Commun. 8, 704– (2017). 20

View on Pith 2017

[51] [51]

Uykur, E., Ortiz, B. R., Wilson, S. D., Dressel, M. & Tsirl in, A. A. Optical detection of the density-wave instability in the kagome metal KV 3Sb5. npj Quantum Mater .7, 16 (2022)

View on Pith 2022

[52] [52]

Zhou, X. et al. Effects of niobium doping on the charge density wave and elec tronic correla- tions in the kagome metal Cs (V1−xNbx)3Sb5. Phys. Rev. B 107, 125124 (2023)

View on Pith 2023

[53] [53]

Zhou, X. et al. Electronic correlations and evolution of the charge densit y wave in the kagome metals AV3Sb5 (A = K, Rb, Cs). Phys. Rev. B 107, 165123 (2023)

View on Pith 2023

[54] [54]

Peierls, R. E. Quantum Theory of Solids (Clarendon, Oxford, 1955)

View on Pith 1955

[55] [55]

Fr¨ ohlich, H. On the theory of superconductivity: the on e-dimensional case. Proc. R. Soc. Lond. A 223, 296 (1954)

View on Pith 1954

[56] [56]

Gr¨ uner, G. The dynamics of charge-density waves. Rev. Mod. Phys. 60, 1129–1181 (1988)

View on Pith 1988

[57] [57]

Gr¨ uner, G. The dynamics of spin-density waves. Rev. Mod. Phys. 66, 1–24 (1994)

View on Pith 1994

[58] [58]

McMillan, W. L. Microscopic model of charge-density wav es in 2 H-TaSe2. Phys. Rev. B 16, 643–650 (1977)

View on Pith 1977

[59] [59]

LaBollita, H., Pardo, V ., Norman, M. R. & Botana, A. S. Ele ctronic structure and magnetic properties of La 3Ni2O7 under pressure. arXiv (2023). arXiv:2309.17279

View on Pith Pith review arXiv 2023

[60] [60]

Xu, B. et al. Optical spectroscopy of the Weyl semimetal TaAs. Phys. Rev. B 93, 121110 (2016)

View on Pith 2016

[61] [61]

Wang, Y ., Kang, C.-J., Miao, H. & Kotliar, G. Hund’s metalphysics: From SrNiO2 to LaNiO2. Phys. Rev. B 102, 161118 (2020). 21

View on Pith 2020

[62] [62]

Kang, C.-J. & Kotliar, G. Optical Properties of the Inﬁni te-Layer La1−xSrxNiO2 and Hidden Hund’s Physics. Phys. Rev. Lett. 126, 127401 (2021)

View on Pith 2021

[63] [63]

Homes, C. C., Reedyk, M., Cradles, D. A. & Timusk, T. Techn ique for measuring the re- ﬂectance of irregular, submillimeter-sized samples. Appl. Opt. 32, 2976–2983 (1993)

View on Pith 1993

[64] [64]

Dressel, M. & Gr¨ uner, G. Electrodynamics of Solids (Cambridge University press, 2002)

View on Pith 2002

[65] [65]

Tanner, D. B. Optical Effeccts in Solids (Cambridge University press, 2019)

View on Pith 2019

[66] [66]

Blaha, P ., Schwarz, K., Madsen, G. K. H., Kvasnicka, D. & L uitz, J. WIEN2K, An Augmented Plane Wave + Local Orbitals Program for Calculating Crystal Properties (Technische Uni- versit¨ at Wien, Vienna, Austria, 2001)

View on Pith 2001

[67] [67]

Perdew, J. P ., Burke, K. & Ernzerhof, M. Generalized Grad ient Approximation Made Simple. Phys. Rev. Lett. 77, 3865–3868 (1996)

View on Pith 1996

[68] [68]

Ling, C. D., Argyriou, D. N., Wu, G. & Neumeier, J. Neutron Diffraction Study of La 3Ni2O7: Structural Relationships Among n = 1, 2, and 3 Phases La n+1NinO3n+1. J. Solid State Chem. 152, 517–525 (2000). Methods Single crystal growth. High-quality single crystals of La 3Ni2O7 were grown by a vertical optical- image ﬂoating zone furnace with an oxygen pres...

View on Pith 2000