pith. sign in

arxiv: 1907.03033 · v1 · pith:VQEDEUK6new · submitted 2019-07-05 · ❄️ cond-mat.str-el · cond-mat.supr-con

Thermodynamic Investigation of Metamagnetism in Pulsed High Magnetic Fields on Heavy Fermion Superconductor UTe₂

Shusaku Imajo , Yoshimitsu Kohama , Atsushi Miyake , Chao Dong , Masashi Tokunaga , Jacques Flouquet , Koichi Kindo , Dai Aoki This is my paper

Pith reviewed 2026-05-25 01:45 UTC · model grok-4.3

classification ❄️ cond-mat.str-el cond-mat.supr-con
keywords UTe2heavy fermionmetamagnetismmagnetocaloric effectquantum fluctuationsheat capacitysuperconductivityhigh magnetic fields
0
0 comments X

The pith

The electronic heat capacity coefficient diverges approaching the metamagnetic transition at 36 T in UTe2, showing that quantum fluctuations enhance the effective mass and support superconductivity in high fields.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper measures heat capacity and magnetocaloric effects in UTe2 under pulsed magnetic fields along the b-axis. It identifies a first-order metamagnetic transition at 36 T and finds that the normal-state electronic heat capacity coefficient gamma_N increases sharply near this field. This divergence is interpreted as evidence that quantum fluctuations grow strong around the transition, increasing the effective mass and enabling the material to remain superconducting at very high magnetic fields. A reader would care because it connects metamagnetism to the stability of superconductivity against magnetic fields through quantum critical behavior.

Core claim

Magnetocaloric effect measurements detect a thermodynamic anomaly at the first-order metamagnetic transition field of 36.0 T. Heat capacity data show the normal-state electronic coefficient gamma_N diverging as the field approaches Hm. The authors conclude that this reflects strong evolution of quantum fluctuations around Hm that assist superconductivity even in extremely high fields.

What carries the argument

The diverging normal-state electronic heat capacity coefficient gamma_N near the metamagnetic transition field, which tracks the growth of quantum fluctuations and effective mass enhancement.

If this is right

  • The metamagnetic transition at 36 T is first-order and its location and character match earlier magnetization results through the Clausius-Clapeyron relation.
  • The effective mass of quasiparticles increases dramatically approaching Hm.
  • Quantum fluctuations intensify near Hm and help sustain superconductivity at fields beyond those where it would normally be suppressed.
  • Thermodynamic measurements in pulsed fields can reliably capture these anomalies without major artifacts.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • If the divergence in gamma_N is confirmed in steady fields, it would strengthen the link between quantum criticality and high-field superconductivity.
  • Similar diverging heat capacity behavior may occur near metamagnetic transitions in other heavy-fermion compounds.
  • The findings suggest that the superconducting state in UTe2 extends to higher fields than previously expected due to these fluctuations.

Load-bearing premise

The magnetocaloric anomaly at 36 T represents a genuine first-order thermodynamic transition that can be directly compared to magnetization data using the magnetic Clausius-Clapeyron relation without significant pulsed-field artifacts.

What would settle it

Observation of no divergence in the electronic heat capacity coefficient as the magnetic field approaches 36 T from below, or evidence that the transition is not first-order, would falsify the claim that quantum fluctuations around Hm assist high-field superconductivity.

Figures

Figures reproduced from arXiv: 1907.03033 by Atsushi Miyake, Chao Dong, Dai Aoki, Jacques Flouquet, Koichi Kindo, Masashi Tokunaga, Shusaku Imajo, Yoshimitsu Kohama.

Figure 2
Figure 2. Figure 2: (Color online) Time profiles of magnetic field and temperature in a magnetocaloric effect measurement in a pulsed-field. At the shaded areas, the sudden heating ∆Tup and ∆Tdown are observed when the magnetic field reaches about 36.0–36.1 T. The time scale of the heating is ∼10 ms that is much less than τ1, implying that the temperature change at the phase bound￾ary can be treated as a nearly adiabatic proc… view at source ↗
Figure 3
Figure 3. Figure 3: (Color online) Temperature dependence of heat capacity plotted as the Cp/T vs. T at various magnetic fields. The thermodynamic anomaly be￾low 1 K at 11.5 T originates from the superconducting transition. The ex￾trapolations of the data points to zero temperature yields γN for each fields. No contribution from the nuclear heat capacity was observed for the present study. 2.5 2.0 1.5 γN(µ0H)/γN(0 T) {A (µ0H)… view at source ↗
Figure 4
Figure 4. Figure 4: (Color online) Magnetic field dependence of γN with scaling by γN at 0 T and the metamagnetic transition field Hm. The red boxes and blue circles represent γN(µ0H)/γN(0 T) measured in this work and estimated in the magnetization study,17) respectively. The green triangles denote the square root of the normalized quadratic term A obtained in the electrical resistivity measurement.18) The inset shows the enl… view at source ↗
Figure 5
Figure 5. Figure 5: (Color online) (a) Calculated TSC as a function of field obtained from the heat capacity and magnetization17) measurements in UTe2. (b) Cal￾culated orbital limits (left-axis) and electrical resistivity18) (right-axis) as a function of field. The orbital limits are obtained by the formula Horb ∼ (m ∗TSC) 2 from the data of the heat capacity and magnetization17) measure￾ments. the discontinuity, but the γN o… view at source ↗
read the original abstract

We investigated the thermodynamic property of the heavy fermion superconductor UTe$_2$ in pulsed high magnetic fields. The superconducting transition in zero field was observed at $T_{\rm c}$=1.65 K as a sharp heat capacity jump. Magnetocaloric effect measurements in pulsed-magnetic fields obviously detected a thermodynamic anomaly accompanied by a first-order metamagnetic transition at $\mu$$_{0}$$H_{\rm m}$=36.0 T when the fields are applied nearly along the hard-magnetization $b$-axis. From the results of heat capacity measurements in magnetic fields, we found a drastic diverging electronic heat capacity coefficient of the normal state $\gamma$$_{\rm N}$ with approaching $H_{\rm m}$. Comparing with the previous works via the magnetic Clausius-Clapeyron relation, we unveil the thermodynamic details of the metamagnetic transition. The enhancement of the effective mass observed as the development of $\gamma_{\rm N}$ indicates that quantum fluctuation strongly evolves around $H_{\rm m}$; it assists the superconductivity emerging even in extremely high fields.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript reports pulsed high-magnetic-field thermodynamic measurements on the heavy-fermion superconductor UTe₂. It identifies a sharp zero-field heat-capacity jump at Tc = 1.65 K, a first-order metamagnetic transition at μ₀Hm = 36.0 T via magnetocaloric effect for fields along the b-axis, and a diverging normal-state electronic specific-heat coefficient γN as Hm is approached from heat-capacity data. The authors compare the entropy jump with prior magnetization results through the magnetic Clausius-Clapeyron relation and interpret the γN enhancement as evidence that quantum fluctuations near Hm assist superconductivity that persists to high fields.

Significance. If the γN divergence is free of pulsed-field artifacts, the work supplies direct thermodynamic identification of the first-order metamagnetic transition and a quantitative link to earlier magnetization data. This strengthens the experimental basis for associating mass enhancement with quantum fluctuations that may stabilize high-field superconductivity in UTe₂. The use of the Clausius-Clapeyron relation to connect thermodynamic and magnetic data is a concrete strength.

major comments (2)
  1. [Heat capacity measurements in magnetic fields] Heat-capacity and magnetocaloric sections: The central claim that γN diverges as Hm is approached rests on C/T data taken in pulsed fields, yet the manuscript provides no sweep-rate dependence, thermal-relaxation times, or DC-field comparison to exclude eddy-current heating artifacts. Such artifacts would directly undermine the reported divergence and the subsequent quantum-fluctuation interpretation.
  2. [Magnetocaloric effect measurements] Magnetocaloric-effect paragraph: The assertion that the anomaly at 36 T is unambiguously first-order and can be compared directly with prior magnetization data via the Clausius-Clapeyron relation assumes negligible non-equilibrium effects from the pulsed environment; no supporting checks are described.
minor comments (2)
  1. [Abstract] Abstract and results: The statement that γN 'diverges' is presented without error bars, raw traces, or quantitative fit parameters, making the strength of the divergence difficult to evaluate.
  2. [Discussion] Discussion: The link between the observed γN growth and 'quantum fluctuations that assist superconductivity' is stated as an indication rather than derived from a specific model or scaling analysis.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the detailed review and for identifying the need for explicit discussion of possible pulsed-field artifacts. We address each major comment below and indicate the revisions planned for the manuscript.

read point-by-point responses

  1. Referee: Heat-capacity and magnetocaloric sections: The central claim that γN diverges as Hm is approached rests on C/T data taken in pulsed fields, yet the manuscript provides no sweep-rate dependence, thermal-relaxation times, or DC-field comparison to exclude eddy-current heating artifacts. Such artifacts would directly undermine the reported divergence and the subsequent quantum-fluctuation interpretation.

    Authors: We agree that the current manuscript does not describe sweep-rate dependence or explicit thermal-relaxation checks, which leaves open the possibility of eddy-current heating. The observed divergence is reproducible across multiple pulses and consistent with the location of the metamagnetic transition seen in the magnetocaloric effect. In the revised manuscript we will add a dedicated paragraph on experimental conditions (typical sweep rates ~50–150 T/s, pulse durations, and sample thermal anchoring) and note that the sharpness of both the superconducting jump and the metamagnetic anomaly argues against significant heating. Direct DC-field comparison is not available in our data set; we will cite existing DC magnetization and specific-heat literature for qualitative consistency. New pulsed-field runs with varied sweep rates are not feasible at present. revision: partial

  2. Referee: Magnetocaloric-effect paragraph: The assertion that the anomaly at 36 T is unambiguously first-order and can be compared directly with prior magnetization data via the Clausius-Clapeyron relation assumes negligible non-equilibrium effects from the pulsed environment; no supporting checks are described.

    Authors: The first-order character is inferred from the discontinuous entropy change that satisfies the magnetic Clausius-Clapeyron relation when compared with published magnetization data. We acknowledge that the manuscript does not explicitly address possible non-equilibrium effects in the pulsed environment. In revision we will insert a short discussion of pulse characteristics (rise time, field homogeneity) and the reproducibility of the anomaly position and sign change in the magnetocaloric signal, which we take as evidence that the system remains close to equilibrium on the timescale of the measurement. No additional experimental checks (e.g., slower pulses) are available. revision: partial

Circularity Check

0 steps flagged

No circularity: experimental measurements are self-contained

full rationale

The paper reports direct experimental observations of heat capacity jumps, magnetocaloric anomalies, and diverging γN extracted from C/T data in pulsed fields. No mathematical derivation chain, parameter fitting, or ansatz is present that reduces to self-defined inputs. The comparison to prior magnetization data via Clausius-Clapeyron uses external measurements and does not make the present thermodynamic claims equivalent to their own inputs by construction. Minor self-references to earlier work on UTe2 are not load-bearing for the central experimental results.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

No free parameters are introduced. The work relies on standard thermodynamic relations (Clausius-Clapeyron) and the conventional interpretation of γ as a measure of effective mass; no new entities are postulated.

axioms (1)
  • domain assumption The magnetocaloric effect in pulsed fields faithfully registers equilibrium thermodynamic anomalies without significant non-equilibrium heating.
    Invoked when the authors identify the 36 T anomaly as first-order on the basis of the magnetocaloric signal.

pith-pipeline@v0.9.0 · 5758 in / 1383 out tokens · 15982 ms · 2026-05-25T01:45:13.510705+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

35 extracted references · 35 canonical work pages

  1. [1]

    Saxena, P

    S.S. Saxena, P. Agarwal, K. Ahilan, F.M. Grosche, R.K.W. Haselwim- mer, M.J. Steiner, E. Pugh, I.R. Walker, S.R. Julian, P. Monthoux, G.G. Lonzarich, A. Huxley, I. Sheikin, D. Braithwaite and J. Flouquet, Nature 406, 587 (2000)

    work page 2000

  2. [2]

    D. Aoki, K. Ishida and J. Flouquet, J. Phys. Soc. Jpn.88, 022001 (2019)

    work page 2019

  3. [3]

    Aoki and J

    D. Aoki and J. Flouquet, J. Phys. Soc. Jpn. 81, 011003 (2012)

    work page 2012

  4. [4]

    D. Aoki, A. Huxley, E. Ressouche, D. Braithwaite, J. Flouquet, J.-P. Bri- son, E. Lhotel and C. Paulsen, Nature 413, 613 (2001)

    work page 2001

  5. [5]

    L ´evy, I

    F. L ´evy, I. Sheikin, B. Grenier and A.D. Huxley, Science 309, 1343 (2005)

    work page 2005

  6. [6]

    L ´evy, I

    F. L ´evy, I. Sheikin and A. Huxley, Nature Physics 3, 460 (2007)

    work page 2007

  7. [7]

    Miyake, D

    A. Miyake, D. Aoki and J. Flouquet, J. Phys. Soc. Jpn. 77, 094709 (2008)

    work page 2008

  8. [8]

    Miyake, D

    A. Miyake, D. Aoki and J. Flouquet, J. Phys. Soc. Jpn. 78, 063703 (2009)

    work page 2009

  9. [9]

    Sherkunov, A.V

    Y . Sherkunov, A.V . Chubukov and J.J. Betouras, Phys. Rev. Lett.121, 097001 (2018)

    work page 2018

  10. [10]

    Taufour, D

    V . Taufour, D. Aoki, G. Knebel and J. Flouquet, Phys. Rev. Lett. 105, 217201 (2010)

    work page 2010

  11. [11]

    Kotegawa, V

    H. Kotegawa, V . Taufour, D. Aoki, G. Knebel and J. Flouquet, J. Phys. Soc. Jpn. 80, 083703 (2011)

    work page 2011

  12. [12]

    D. Aoki, T. Combier, V . Taufour, T.D. Matsuda, G. Knebel, H. Kotegawa and J. Flouquet, J. Phys. Soc. Jpn. 80, 094711 (2011)

    work page 2011

  13. [13]

    Kimura, N

    N. Kimura, N. Kabeya, H. Aoki, K. Ohyama, M. Maeda, H. Fujii, M. Kogure, T. Asai, T. Komatsubara, T. Yamamura and I. Satoh, Phys. Rev. B 92, 035106 (2015)

    work page 2015

  14. [14]

    S. Ran, C. Eckberg, Q.-P. Ding, Y . Furukawa, T. Metz, S. R. Saha, I. -L. Liu, M. Zic, H. Kim, J. Paglione, and N. P. Butch, arXiv:1811.11808

    work page arXiv

  15. [15]

    D. Aoki, A. Nakamura, F. Honda, D. X. Li, Y . Homma, Y . Shimizu, Y . J. Sato, G. Knebel, J.-P. Brison, A. Pourret, D. Braithwaite, G. Lapertot, Q. Niu, M. Valiˇska, H. Harima, and J. Flouquet, J. Phys. Soc. Jpn. 88, 043702 (2019)

    work page 2019

  16. [16]

    Sundar, S

    S. Sundar, S. Gheidi, K. Akintola, A. M. C ˆot´e, S. R. Dunsiger, S. Ran, 4 J. Phys. Soc. Jpn. LETTERS N. P. Butch, S. R. Saha, J. Paglione, and J. E. Sonier, arXiv:1905.06901

    work page arXiv 1905

  17. [17]

    Miyake, Y

    A. Miyake, Y . Shimizu, Y . J. Sato, D.X. Li, A. Nakamura, Y . Homma, F. Honda, J. Flouquet, M. Tokunaga, and D. Aoki, J. Phys. Soc. Jpn.88, 063706 (2019)

    work page 2019

  18. [18]

    Knafo, M

    W. Knafo, M. Valiˇska, D. Braithwaite, G. Lapertot, G. Knebel, A. Pour- ret, J.-P. Brison, J. Flouquet, D. Aoki, J. Phys. Soc. Jpn. 88, 063705 (2019)

    work page 2019

  19. [19]

    Ran ,I-L

    S. Ran ,I-L. Liu, Y . S. Eo, D. J. Campbell, P. Neves, W. T. Fuhrman, S. R. Saha, C. Eckberg, H. Kim, J. Paglione, D. Graf, J. Singleton and N. P. Butch, arXiv:1905.04343

    work page arXiv 1905

  20. [20]

    Knebel, W

    G. Knebel, W. Knafo, A. Pourret, Q. Niu, M. ValiÅka, D. Braithwaite, G. Lapertot, M. Nardone, A. Zitouni, S. Mishra, I. Sheikin, G. Seyfarth, J.-P. Brison, D. Aoki, and J. Flouquet, J. Phys. Soc. Jpn. 88, 063707 (2019)

    work page 2019

  21. [22]

    Kohama, H

    Y . Kohama, H. Ishikawa, A. Matsuo, K. Kindo, N. Shannon, and Z. Hi- roi, Proc. Natl. Acad. Sci. USA, 116 10686 (2019)

    work page 2019

  22. [23]

    L. Jiao, M. Smidman, Y . Kohama, Z. S. Wang, D. Graf, Z. F. Weng, Y . J. Zhang, A. Matsuo, E. D. Bauer, Hanoh Lee, S. Kirchner, J. Singleton, K. Kindo, J. Wosnitza, F. Steglich, J. D. Thompson, and H. Q. Yuan, Phys. Rev. B 99, 045127 (2019)

    work page 2019

  23. [25]

    (Supplemental Material) The details of the present heat capacity mea- surements are provided online

    work page

  24. [26]

    A. V . Silhanek, M. Jaime, N. Harrison, V . R. Fanelli, C. D. Batista, H. Amitsuka, S. Nakatsuji, L. Balicas, K. H. Kim, Z. Fisk, J. L. Sarrao, L. Civale, and J. A. Mydosh, Phys. Rev. Lett. 96, 136403 (2006)

    work page 2006

  25. [27]

    Kadowaki and S

    K. Kadowaki and S. B. Woods, Solid State Commun. 58, 507 (1986)

    work page 1986

  26. [28]

    Moriya, Acta Phys

    T. Moriya, Acta Phys. Pol. B 34, 287 (2003)

    work page 2003

  27. [29]

    Y . Aoki, T. D.Matsuda, H. Sugawara, H. Sato, H. Ohkuni, R. Settai, Y . ¯Onuki, E. Yamamoto, Y . Haga, A. V . Andreev, V . Sechovsky, L. Havela, H. Ikeda, K. Miyake, J. Magn. Magn. Mater. 177-181, 271 (1998)

    work page 1998

  28. [30]

    Sheikin, A

    I. Sheikin, A. Huxley, D. Braithwaite, J.P. Brison, S. Watanabe, K. Miyake and J. Flouquet, Phys. Rev. B 64, 220503 (2001)

    work page 2001

  29. [31]

    Flouquet, P

    J. Flouquet, P. Haen, F. Lapierre, C. Fierz, A. Amato and D. Jaccard, J. Magn. Magn. Mater. 76&77, 285 (1988)

    work page 1988

  30. [32]

    Hardy, D

    F. Hardy, D. Aoki, C. Meingast, P. Schweiss, P. Burger, H. v. Loehneysen and J. Flouquet, Phys. Rev. B 83, 195107 (2011)

    work page 2011

  31. [33]

    Nakamura, T

    S. Nakamura, T. Sakakibara, Y . Shimizu, S. Kittaka, Y . Kono, Y . Haga, J. Posp´ıˇsil and E. Yamamoto, Phys. Rev. B96, 094411 (2017). 5 J. Phys. Soc. Jpn. LETTERS Supplemental Material for Thermodynamic Investigation of Metamagnetism in Pulsed High Magnetic Fields on Heavy Fermion Superconductor UTe 2 In this supplemental material, the details of heat ca...

    work page 2017

  32. [34]

    Kohama, and K

    Y . Kohama, and K. Kindo, Rev. Sci. Instrum. 86, 104701 (2015)

    work page 2015

  33. [35]

    Kohama, Y

    Y . Kohama, Y . Hashimoto, S. Katsumoto, M. Tokunaga and K. Kindo, Meas. Sci. Technol. 24, 115005 (2013)

    work page 2013

  34. [36]

    Kohama, H

    Y . Kohama, H. Ishikawa, A. Matsuo, K. Kindo, N. Shannon, and Z. Hi- roi, Proc. Natl. Acad. Sci. USA, 116, 10686 (2019)

    work page 2019

  35. [37]

    L. Jiao, M. Smidman, Y . Kohama, Z. S. Wang, D. Graf, Z. F. Weng, Y . J. Zhang, A. Matsuo, E. D. Bauer, Hanoh Lee, S. Kirchner, J. Singleton, K. Kindo, J. Wosnitza, F. Steglich, J. D. Thompson, and H. Q. Yuan, Phys. Rev. B 99, 045127 (2019). 6

    work page 2019