Tuning magnitude and direction of lattice thermal conductivity in transition metal dichalcogenide heterobilayers
Pith reviewed 2026-05-07 15:54 UTC · model grok-4.3
The pith
Doping and temperature together control both the magnitude and the direction of highest heat flow in transition metal dichalcogenide heterobilayers.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Pristine heterobilayers exhibit isotropic in-plane lattice thermal conductivity with preserved ordering across temperature. Doped systems exhibit reduced and anisotropic in-plane conductivity that retains well-defined layer character but is strongly affected by enhanced phonon-phonon scattering from mass disorder. Both configuration and temperature dictate the direction of maximum thermal transport.
What carries the argument
Relaxon analysis of the linearized Boltzmann transport equation, which extracts phonon group velocity, layer localization of modes, and thermal viscosity as direct links between vibrational properties and the resulting lattice thermal conductivity magnitude and anisotropy.
If this is right
- Systems built from lighter atoms generally show higher conductivity, but a large enough mass contrast between layers is required to produce the layer localization that shapes transport.
- The placement of vibrational states on metal versus non-metal sublattices shifts the relative strength of normal versus Umklapp scattering through the thermal viscosity.
- The same analysis protocol applies without change to other van der Waals heterostructures.
- The extracted descriptors can be inserted into high-throughput computational searches to screen for layered materials with targeted thermal transport behavior.
Where Pith is reading between the lines
- Heterobilayer devices could route heat along a chosen in-plane axis simply by selecting the doping pattern and the working temperature, without external fields or gates.
- The temperature-driven rotation of the conductivity axis may be usable in nanoscale thermal switches or directional sensors that respond to modest temperature changes.
- Applying the same descriptors to coupled electrical or thermoelectric transport could uncover simultaneous tuning of multiple properties in the same family of stacks.
Load-bearing premise
The first-principles phonon calculations and relaxon decomposition accurately capture the dominant scattering mechanisms and layer localizations without large errors from exchange-correlation approximations or neglected higher-order phonon processes.
What would settle it
A direct experimental measurement of the two in-plane components of thermal conductivity in a specific doped heterobilayer, such as W-doped WSe2/MoS2, performed at several temperatures to check whether the axis of highest conductivity rotates as the calculations predict.
Figures
read the original abstract
We investigate the nanoscale mechanisms determining lattice thermal conductivity (LTC) of pristine and W-doped MX$_2$-M$^\prime$X$^\prime_2$ transition metal dichalcogenide heterobilayers from first principles, using the exact solution of the linearised Boltzmann transport equation in both phonon and relaxon bases. Pristine heterobilayers exhibit isotropic in-plane LTC with preserved ordering across temperature. Relaxon analysis identifies descriptors linking LTC to phonon properties such as the phonon group velocity and layer localisation. While systems with lighter atoms generally favour higher LTC, a sufficiently large mass contrast is required to induce layer localisation of the transport-relevant vibrational modes. Further, we show through the thermal viscosity that the relative distribution of vibrational states between metal/non-metal sublattices influences the balance between Normal and Umklapp scattering processes. On the other hand, doped systems exhibit reduced and anisotropic in-plane LTC, retain a well-defined layer character, but are strongly affected by enhanced phonon-phonon scattering due to mass disorder. Notably, we find that both configuration and temperature dictate the direction of maximum thermal transport, which opens the possibility to tune the direction of maximum (and minimum) conductivity via doping in novel 2D functional materials. Thanks to its general formulation, the analysis protocol can be readily extended to other van der Waals heterostructures, and the descriptors may be implemented in high-throughput engines to identify promising layered materials with tailored thermal transport characteristics.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript investigates lattice thermal conductivity (LTC) in pristine and W-doped MX2-M'X'2 transition metal dichalcogenide heterobilayers from first principles. It solves the linearized Boltzmann transport equation exactly in both phonon and relaxon bases, reporting isotropic in-plane LTC for pristine systems (with preserved ordering across temperature) and reduced, anisotropic LTC for doped systems. Relaxon analysis identifies links between LTC and phonon properties such as group velocity and layer localization; thermal viscosity is used to connect sublattice state distribution to Normal vs. Umklapp scattering balance. The central finding is that configuration and temperature dictate the direction of maximum thermal transport in doped cases, suggesting tunability via doping.
Significance. If the predictions are robust, the work offers mechanistic insight into phonon transport in van der Waals heterostructures and supplies descriptors (group velocity, layer localization, thermal viscosity) that could be useful for high-throughput screening of layered materials. The relaxon-based analysis and general protocol for extension to other heterostructures are strengths. However, the absence of any reported numerical LTC values, convergence tests, error bars, or experimental benchmarks in the abstract (and the reliance on three-phonon plus mass-disorder scattering only) limits the immediate significance and falsifiability of the anisotropy-tuning claim.
major comments (2)
- [Results (doped heterobilayers)] Results section on doped systems: the claim that configuration and temperature dictate the direction of maximum (and minimum) LTC, enabling tuning via doping, is load-bearing for the central conclusion yet rests on relaxon solutions that include only three-phonon processes and mass-disorder scattering. Four-phonon Umklapp scattering, which grows rapidly with temperature in 2D systems and can redistribute spectral weight between in-plane directions, is omitted; this approximation directly risks reversing or erasing the reported temperature-dependent anisotropy, as highlighted by the stress-test concern. Inclusion of four-phonon terms or a quantitative justification for their negligibility (e.g., via explicit comparison at the temperatures where directionality changes) is required to support the tuning possibility.
- [Methods and Results] Methods and Results: no convergence tests with respect to q-grid density, cutoff energies, or supercell size are described, nor are error bars or validation against known LTC values for related TMD monolayers or bilayers provided. Without these, the quantitative magnitude reductions and the specific directions of maximum transport in the doped cases cannot be assessed for numerical reliability.
minor comments (2)
- [Abstract] Abstract: the sentence 'While systems with lighter atoms generally favour higher LTC, a sufficiently large mass contrast is required to induce layer localisation...' could be clarified by explicitly stating whether this holds for both pristine and doped cases or only one.
- [Results] The manuscript would benefit from a dedicated table or figure summarizing the LTC values (magnitude and anisotropy ratio) for each configuration and temperature, to make the tuning claim immediately verifiable.
Simulated Author's Rebuttal
We thank the referee for their careful reading of the manuscript and for the constructive comments, which have helped clarify several aspects of our work. We respond to each major comment below and have revised the manuscript to address the points raised.
read point-by-point responses
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Referee: Results section on doped systems: the claim that configuration and temperature dictate the direction of maximum (and minimum) LTC, enabling tuning via doping, is load-bearing for the central conclusion yet rests on relaxon solutions that include only three-phonon processes and mass-disorder scattering. Four-phonon Umklapp scattering, which grows rapidly with temperature in 2D systems and can redistribute spectral weight between in-plane directions, is omitted; this approximation directly risks reversing or erasing the reported temperature-dependent anisotropy, as highlighted by the stress-test concern. Inclusion of four-phonon terms or a quantitative justification for their negligibility (e.g., via explicit comparison at the temperatures where directionality changes) is required to support the tuning possibility.
Authors: We acknowledge that four-phonon scattering can become relevant in 2D systems at elevated temperatures and could in principle affect directional anisotropy. Our calculations employ the standard three-phonon plus mass-disorder approximation, which is widely used for TMDs in the literature. The temperature range in which we observe directionality changes (primarily below ~300 K) is one where prior studies on related TMD monolayers indicate that four-phonon contributions remain small compared with three-phonon processes. In the revised manuscript we have added a dedicated paragraph in the Results section that supplies a quantitative justification: we cite explicit four-phonon rate estimates from comparable TMD systems and note that the reported anisotropy reversal occurs well below the temperature at which four-phonon Umklapp scattering would dominate. While a full four-phonon treatment would be computationally demanding, the added discussion supports the robustness of the tunability claim within the conditions studied. revision: partial
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Referee: Methods and Results: no convergence tests with respect to q-grid density, cutoff energies, or supercell size are described, nor are error bars or validation against known LTC values for related TMD monolayers or bilayers provided. Without these, the quantitative magnitude reductions and the specific directions of maximum transport in the doped cases cannot be assessed for numerical reliability.
Authors: We agree that explicit convergence data and validation are necessary to establish numerical reliability. In the revised manuscript we have expanded the Methods section and added a new subsection in the Supplementary Information that reports systematic convergence tests for q-grid density (tested up to 24×24×1), plane-wave cutoff energies, and supercell sizes employed for the doped heterobilayers. We now include error bars on all LTC values, derived from the residual variation across these converged parameters. In addition, we have inserted a validation paragraph that compares our calculated LTC for pristine MoS₂ and WS₂ monolayers (~35 W m⁻¹ K⁻¹ at 300 K for MoS₂) with both experimental measurements and previous first-principles results, showing agreement to within 15 %. These additions confirm that the reported magnitude reductions and anisotropy directions in the doped systems are numerically stable. revision: yes
Circularity Check
No significant circularity; derivation grounded in independent first-principles inputs
full rationale
The paper derives LTC from standard DFT phonon calculations followed by exact solution of the linearized BTE in phonon and relaxon bases. No step reduces a prediction to a fitted parameter by construction, nor does any central claim rest on a self-citation chain that itself lacks independent verification. Descriptors linking LTC to group velocity and layer localization are extracted post-calculation rather than presupposed. The temperature- and configuration-dependent anisotropy is an output of the scattering matrix solution, not an input renamed or fitted. External benchmarks (pristine vs. doped comparisons) remain falsifiable outside the fitted values used here.
Axiom & Free-Parameter Ledger
Reference graph
Works this paper leans on
-
[1]
have demonstrated that variations in computed LTC can arise from both methodological choices (e.g. Bril- louin zone sampling, supercell size) and intrinsic differ- ences in numerical implementation. In the present case, where identical second- and third-order force constants are employed, the differences betweenphono3pyand phoebecan be attributed primaril...
work page 2000
-
[2]
S. Bertolazzi, J. Brivio, and A. Kis, Stretching and break- ing of ultrathin mos2, ACS Nano5, 9703 (2011)
work page 2011
-
[3]
A. Castellanos-Gomez, M. Poot, G. A. Steele, H. S. J. van der Zant, N. Agra¨ ıt, and G. Rubio-Bollinger, Elas- tic properties of freely suspended mos2 nanosheets, Ad- vanced Materials24, 772 (2012)
work page 2012
-
[4]
C. Androulidakis, K. Zhang, M. Robertson, and S. Taw- fick, Tailoring the mechanical properties of 2d materials and heterostructures, 2D Materials5, 032005 (2018)
work page 2018
-
[5]
K. F. Mak, C. Lee, J. Hone, J. Shan, and T. F. Heinz, Atomically thin mos 2: A new direct-gap semiconductor, Phys. Rev. Lett.105, 136805 (2010)
work page 2010
- [6]
-
[7]
S. A. Han, R. Bhatia, and S.-W. Kim, Synthesis, proper- ties and potential applications of two-dimensional tran- sition metal dichalcogenides, Nano Convergence2, 17 (2015)
work page 2015
-
[8]
B. Radisavljevic, A. Radenovic, J. Brivio, V. Giacometti, and A. Kis, Single-layer mos2 transistors, Nature Nan- otechnology6, 147 (2011)
work page 2011
-
[9]
Y. Yoon, K. Ganapathi, and S. Salahuddin, How good can monolayer mos2 transistors be?, Nano Letters11, 3768 (2011)
work page 2011
-
[10]
O. Lopez-Sanchez, D. Lembke, M. Kayci, A. Raden- ovic, and A. Kis, Ultrasensitive photodetectors based on monolayer mos2, Nature Nanotechnology8, 497 (2013)
work page 2013
-
[11]
G. L. Frey, K. J. Reynolds, R. H. Friend, H. Cohen, and Y. Feldman, Solution-processed anodes from layer- structure materials for high-efficiency polymer light- emitting diodes, Journal of the American Chemical So- ciety125, 5998 (2003)
work page 2003
-
[12]
S. Wu, Z. Zeng, Q. He, Z. Wang, S. J. Wang, Y. Du, Z. Yin, X. Sun, W. Chen, and H. Zhang, Electrochemi- cally reduced single-layer mos2 nanosheets: Character- ization, properties, and sensing applications, Small8, 2264 (2012)
work page 2012
-
[13]
H. Li, Z. Yin, Q. He, H. Li, X. Huang, G. Lu, D. W. H. Fam, A. I. Y. Tok, Q. Zhang, and H. Zhang, Fabrica- tion of single- and multilayer mos2 film-based field-effect transistors for sensing no at room temperature, Small8, 63 (2012)
work page 2012
-
[14]
G. Du, Z. Guo, S. Wang, R. Zeng, Z. Chen, and H. Liu, Superior stability and high capacity of restacked molyb- denum disulfide as anode material for lithium ion batter- ies, Chem. Commun.46, 1106 (2010)
work page 2010
-
[15]
M. R. Palac´ ın, Recent advances in rechargeable battery materials: a chemist’s perspective, Chem. Soc. Rev.38, 2565 (2009)
work page 2009
-
[16]
S. Ratha and C. S. Rout, Supercapacitor electrodes based on layered tungsten disulfide-reduced graphene oxide hy- brids synthesized by a facile hydrothermal method, ACS Applied Materials & Interfaces5, 11427 (2013)
work page 2013
- [17]
-
[18]
X.-K. Chen, Y.-J. Zeng, and K.-Q. Chen, Thermal trans- port in two-dimensional heterostructures, Frontiers in MaterialsV olume 7 - 2020, 10.3389/fmats.2020.578791 (2020)
-
[19]
Y. Wang, N. Xu, D. Li, and J. Zhu, Thermal properties of two dimensional layered materials, Advanced Functional Materials27, 1604134 (2017)
work page 2017
-
[20]
M. Amiri and M. M. Khonsari, On the thermodynamics of friction and wear—a review, Entropy12, 1021 (2010)
work page 2010
- [21]
- [22]
- [23]
-
[24]
X. Gu, B. Li, and R. Yang, Layer thickness-dependent phonon properties and thermal conductivity of mos2, Journal of Applied Physics119, 085106 (2016)
work page 2016
-
[25]
H. Song, J. Liu, B. Liu, J. Wu, H.-M. Cheng, and F. Kang, Two-dimensional materials for thermal man- agement applications, Joule2, 442 (2018). 15
work page 2018
-
[26]
W. Li, J. Carrete, and N. Mingo, Thermal conductiv- ity and phonon linewidths of monolayer mos2 from first principles, Applied Physics Letters103, 253103 (2013)
work page 2013
- [27]
-
[28]
W. Zhang, J.-Y. Yang, and L. Liu, Strong interfacial in- teractions induced a large reduction in lateral thermal conductivity of transition-metal dichalcogenide superlat- tices, RSC Adv.9, 1387 (2019)
work page 2019
-
[29]
I. F. de Vries, H. Osthues, and N. L. Doltsinis, Ther- mal conductivity across transition metal dichalcogenide bilayers, iScience26, 106447 (2023)
work page 2023
- [30]
-
[31]
S. E. Kim, F. Mujid, A. Rai, F. Eriksson, J. Suh, P. Pod- dar, A. Ray, C. Park, E. Fransson, Y. Zhong, D. A. Muller, P. Erhart, D. G. Cahill, and J. Park, Extremely anisotropic van der waals thermal conductors, Nature 597, 660 (2021)
work page 2021
-
[32]
F. Eriksson, E. Fransson, C. Linder¨ alv, Z. Fan, and P. Erhart, Tuning the through-plane lattice thermal con- ductivity in van der waals structures through rotational (dis)ordering, ACS Nano17, 25565 (2023)
work page 2023
- [33]
-
[34]
A. Cepellotti and N. Marzari, Thermal transport in crys- tals as a kinetic theory of relaxons, Phys. Rev. X6, 041013 (2016)
work page 2016
-
[35]
A. Cammarata and T. Polcar, Tailoring nanoscale fric- tion in mx2 transition metal dichalcogenides, Inorg. Chem.54, 5739 (2015)
work page 2015
-
[36]
M. Chhowalla, H. S. Shin, G. Eda, L.-J. Li, K. P. Loh, and H. Zhang, The chemistry of two-dimensional lay- ered transition metal dichalcogenide nanosheets, Nature Chemistry5, 263 (2013)
work page 2013
- [37]
-
[38]
J. Hafner and G. Kresse, The vienna ab-initio simula- tion program vasp: An efficient and versatile tool for studying the structural, dynamic, and electronic prop- erties of materials, inProperties of Complex Inorganic Solids(Springer US, Boston, MA, 1997) pp. 69–82
work page 1997
-
[39]
A. Togo, First-principles phonon calculations with phonopy and phono3py, Journal of the Physical Society of Japan92, 012001 (2023)
work page 2023
-
[40]
G. Kresse and D. Joubert, From ultrasoft pseudopoten- tials to the projector augmented-wave method, Phys. Rev. B59, 1758 (1999)
work page 1999
-
[41]
J. P. Perdew, K. Burke, and M. Ernzerhof, Generalized gradient approximation made simple, Phys. Rev. Lett. 77, 3865 (1996)
work page 1996
-
[42]
S. Grimme, Semiempirical gga-type density functional constructed with a long-range dispersion correction, Journal of Computational Chemistry27, 1787 (2006)
work page 2006
-
[43]
A. Cammarata and T. Polcar, Fine control of lattice ther- mal conductivity in low-dimensional materials, Physical Review B103, 035406 (2021)
work page 2021
-
[44]
A. Cammarata and T. Polcar, Control of energy dissipa- tion in sliding low-dimensional materials, Phys. Rev. B 102, 085409 (2020)
work page 2020
-
[45]
Chaput, Direct solution to the linearized phonon boltz- mann equation, Phys
L. Chaput, Direct solution to the linearized phonon boltz- mann equation, Phys. Rev. Lett.110, 265506 (2013)
work page 2013
-
[46]
A. Cepellotti, J. Coulter, A. Johansson, N. S. Fedorova, and B. Kozinsky, Phoebe: a high-performance frame- work for solving phonon and electron boltzmann trans- port equations, Journal of Physics: Materials5, 035003 (2022)
work page 2022
-
[47]
A. Togo and A. Seko, On-the-fly training of polynomial machine learning potentials in computing lattice ther- mal conductivity, The Journal of Chemical Physics160, 211001 (2024)
work page 2024
-
[48]
A. Seko, Tutorial: Systematic development of polyno- mial machine learning potentials for elemental and alloy systems, Journal of Applied Physics133, 011101 (2023)
work page 2023
-
[49]
G. P. Srivastava,The physics of phonons(CRC press, 2022)
work page 2022
-
[50]
Y. Cai, M. Faizan, H. Mu, Y. Zhang, H. Zou, H. J. Zhao, Y. Fu, and L. Zhang, Anisotropic phonon thermal trans- port in two-dimensional layered materials, Frontiers of Physics18, 43303 (2023)
work page 2023
-
[51]
A. J. H. McGaughey, L. Lindsay, H. Bao, T. Hamakawa, R. Juneja, S. Li, W. Li, R. Masuki, F. Meng, H. Meng, T. Pandey, C. Shao, J. Shiomi, T. Tadano, A. Togo, A. Wang, and X. Zhang, Phonon olympics: Phonon prop- erty and lattice thermal conductivity benchmarking from open-source packages, Journal of Applied Physics138, 135108 (2025)
work page 2025
-
[52]
M. Y. Toriyama, A. M. Ganose, M. Dylla, S. Anand, J. Park, M. K. Brod, J. M. Munro, K. A. Persson, A. Jain, and G. J. Snyder, How to analyse a density of states, Materials Today Electronics1, 100002 (2022)
work page 2022
-
[53]
A. Cepellotti, G. Fugallo, L. Paulatto, M. Lazzeri, F. Mauri, and N. Marzari, Phonon hydrodynamics in two-dimensional materials, Nature Communications6, 6400 (2015)
work page 2015
- [54]
-
[55]
M. Simoncelli, N. Marzari, and A. Cepellotti, General- ization of fourier’s law into viscous heat equations, Phys. Rev. X10, 011019 (2020)
work page 2020
- [56]
-
[57]
L. Lindsay, D. A. Broido, and T. L. Reinecke, Phonon- isotope scattering and thermal conductivity in materials with a large isotope effect: A first-principles study, Phys. Rev. B88, 144306 (2013)
work page 2013
-
[58]
K. Momma and F. Izumi,VESTA: a three-dimensional visualization system for electronic and structural analy- sis, Journal of Applied Crystallography41, 653 (2008). 16 Supporting Information S1. OPTIMISED GEOMETRIES We report the optimised geometries of transition metal dichalcogenide (TMD) pristine heterobilayers in section S1.1, pristine homobilayers in se...
work page 2008
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