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

TL;DR

This study uncovers the intrinsic origin of strong anisotropic thermal transport in bulk CrOCl, linking it to electronic structure and electron distribution, with implications for designing advanced thermal materials.

Contribution

It combines experimental and computational methods to reveal the fundamental electronic origin of thermal anisotropy in bulk CrOCl, a novel insight in the field.

Findings

In-plane thermal conductivity at 300 K is 21.6 W/mK.

Cross-plane thermal conductivity at 300 K is 2.18 W/mK.

Electrons are mainly distributed in-plane, causing anisotropic heat transfer.

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 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 ($\kappa$) at 300 K are found to be 21.6 and 2.18 Wm$^{-1}$K$^{-1}$, respectively, showcasing a strong $\kappa_\mathrm{in-plane}/\kappa_\mathrm{cross-plane}$ ratio of $\sim$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 sheds light on the design of advanced thermal functional materials.