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Charge fluctuations above TCDW revealed by glasslike thermal transport in kagome metals AV3Sb5 (A=K,Rb,Cs)

Kunya Yang, Wei Xia, Xinrun Mi, Long Zhang, Yuhan Gan, Aifeng Wang, Yisheng Chai, Xiaoyuan Zhou, Xiaolong Yang, Yanfeng Guo, and Mingquan He
Phys. Rev. B 107, 184506 – Published 11 May 2023
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  • INTRODUCTION
  • EXPERIMENTAL METHOD
  • RESULTS AND DISCUSSION
  • CONCLUSIONS
  • ACKNOWLEDGMENTS
    • Supplemental Material
    References

    Abstract

    We present heat capacity, electrical, and thermal transport measurements of kagome metals AV3Sb5 (A=K,Rb,Cs). In all three compounds, the development of short-range charge fluctuations above the charge density wave (CDW) transition temperature TCDW strongly scatters phonons via the electron-phonon coupling, leading to the glasslike phonon heat transport, i.e., the phonon thermal conductivity decreases weakly upon cooling. Once the long-range charge order sets in below TCDW, short-range charge fluctuations are quenched, and the typical Umklapp scattering dominated phonon heat transport is recovered. The charge-fluctuations-induced glasslike phonon thermal conductivity implies sizable electron-phonon coupling in AV3Sb5.

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    • Received 8 November 2022
    • Revised 26 March 2023
    • Accepted 28 April 2023

    DOI:https://doi.org/10.1103/PhysRevB.107.184506

    ©2023 American Physical Society

    Physics Subject Headings (PhySH)

    1. Research Areas
    Charge density wavesSuperconductivityThermal conductivity
    1. Techniques
    Transport techniques
    Condensed Matter, Materials & Applied Physics

    Authors & Affiliations

    Kunya Yang1,*, Wei Xia2,3,*, Xinrun Mi1, Long Zhang1, Yuhan Gan1, Aifeng Wang1, Yisheng Chai1, Xiaoyuan Zhou1, Xiaolong Yang1,†, Yanfeng Guo2,‡, and Mingquan He1,§

    • 1Low Temperature Physics Lab, College of Physics and Center of Quantum Materials and Devices, Chongqing University, Chongqing 401331, China
    • 2School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
    • 3ShanghaiTech Laboratory for Topological Physics, Shanghai 201210, China

    • *These authors contributed equally to this work.
    • †yangxl@cqu.edu.cn
    • ‡guoyf@shanghaitech.edu.cn
    • §mingquan.he@cqu.edu.cn

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    Vol. 107, Iss. 18 — 1 May 2023

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    Images

    • Figure 1
      Figure 1

      Temperature dependence of the specific heat Cp of (a) KV3Sb5, (b) RbV3Sb5, and (c) CsV3Sb5. The arrows point out the CDW transitions. Insets in (a)–(c) plot the linear fitting (black dashed lines) of the specific heat according to Cp/T=γ+βT2 within a temperature range of 2–4.5 K.

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    • Figure 2
      Figure 2

      In-plane longitudinal thermal conductivity (κxx) and electrical resistivity (ρxx) of (a) KV3Sb5, (b) RbV3Sb5, and (c) CsV3Sb5. The CDW transitions in the three systems are labeled by vertical dashed lines. Sizable thermal and electrical magnetoconductivity only appear in the CDW state. Black dash-dotted lines are guides to the eye.

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    • Figure 3
      Figure 3

      Thermal magnetoconductivity (a)–(c) and electrical magnetoconductivity (d)–(f) of AV3Sb5 measured at fixed temperatures. External magnetic fields were applied along the c axis (B∥c). In all three compounds, κxx(B) and σxx(B) share similar magnetic field dependence, implying an electronic origin of the thermal magnetoconductivity.

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    • Figure 4
      Figure 4

      (a)–(c) Scaling of κxx(B) vs σxx(B)T using the magnetoconductivity data shown in Fig. 3. Solid black lines are linear fittings, from which the Lorenz number can be extracted according to Eq. (1). (d) The estimated Lorenz number as a function of temperature. Solid lines are guides to the eye. Below about 80 K, the Lorenz number deviates from the degenerate value L0 and is strongly enhanced at low temperatures.

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    • Figure 5
      Figure 5

      (a) Temperature dependence of phonon thermal conductivity κph in AV3Sb5 obtained after subtracting the electronic contributions from the total thermal conductivity. The black triangles mark the CDW transitions. Black dashed lines are theoretical modelings of κph below TCDW following the Debye-Callaway approach by considering the conventional phonon scattering mechanisms. Above TCDW, κph is well described by incorporating the scattering of phonons by charge-fluctuations-induced local lattice distortions via EPC (solid black lines). (b)Temperature dependence of the phonon mean free path (ℓ) of AV3Sb5.

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