Asymmetric electron distribution induced intrinsically strong anisotropy of thermal transport in bulk CrOCl

Abstract

Anisotropic heat transfer offers promising solutions to the efficient heat dissipation in the realm of electronic device thermal management. However, the fundamental origin of the anisotropy of thermal transport remains mysterious. In this paper, by combining the frequency domain thermoreflectance (FDTR) technique and first-principles based multiscale simulations, we report the intrinsic anisotropy of thermal transport in bulk CrOCl, and further trace the origin of the anisotropy back to the fundamental electronic structures. The in-plane and cross-plane thermal conductivities (κ) at 300 K are found to be 21.6 and 2.18 W m⁻¹ K⁻¹, respectively, showcasing a strong κ_in-plane/κ_cross-plane ratio of ∼10. Deep analysis of orbital-resolved electronic structures reveals that electrons are mainly distributed along the in-plane direction with limited interlayer distribution along the cross-plane direction, fundamentally leading to the intrinsic anisotropy of thermal transport in bulk CrOCl. The insight gained in this work would shed light on the atomic-scale design of advanced thermal functional materials.