Affiliation: | 1. College of Physics & Center of Quantum Materials and Devices & Analytical and Testing Center, Chongqing University, Chongqing, 41331 China;2. School of Science, Chongqing University of Posts and Telecommunications, Chongqing, 400065 China;3. Ultrafast Electron Microscopy Laboratory, The MOE Key Laboratory of Weak-Light Nonlinear Photonics, School of Physics, Nankai University, Tianjin, 300071 China Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190 China;4. Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, D-85747 Garching, Germany;5. State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 China;6. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190 China Tiangong University, Tianjin, 300387 China |
Abstract: | Layered van der Waals (vdW) magnets are prominent playgrounds for developing magnetoelectric, magneto-optic, and spintronic devices. In spintronics, particularly in spincaloritronic applications, low thermal conductivity (κ) is highly desired. Herein, by combining thermal transport measurements with density functional theory calculations, this study demonstrates low κ down to 1 W m−1 K−1 in a typical vdW ferromagnet Cr2Si2Te6. In the paramagnetic state, development of magnetic fluctuations way above Tc = 33 K strongly reduces κ via spin-phonon scattering, leading to low κ ≈ 1 W m−1 K−1 over a wide temperature range, in comparable to that of amorphous silica. In the magnetically ordered state, emergence of resonant magnon-phonon scattering limits κ below ≈2 W m−1 K−1, which will be three times larger if magnetic scatterings are absent. Application of magnetic fields strongly suppresses the spin-phonon scattering, giving rise to large enhancements of κ. This study's calculations well capture these complex behaviors of κ by taking the temperature- and magnetic-field-dependent spin-phonon scattering into account. Realization of low κ, which is easily tunable by magnetic fields in Cr2Si2Te6, may further promote spincaloritronic applications of vdW magnets. This study's theoretical approach may also provide a generic understanding of spin-phonon scattering, which appears to play important roles in various systems. |