Phonon heat conduction across slippery interfaces in twisted graphite

TL;DR

This study experimentally investigates phonon heat conduction across slippery twisted interfaces in graphite, revealing significant suppression of thermal conductance and highlighting the role of transverse acoustic phonons, with implications for thermal management in twistronics.

Contribution

The paper introduces novel experimental techniques to measure interfacial thermal transport in twisted graphite, demonstrating the impact of interface slipperiness on heat conduction.

Findings

Over 30-fold suppression of thermal conductance at slippery interfaces

Interfacial conductance exceeds 600 MW/m²K, surpassing artificial vdW structures

Transverse acoustic phonons play a key role in heat transfer

Abstract

Interlayer rotation in van der Waals (vdW) materials offers great potential for manipulating phonon dynamics and heat flow in advanced electronics with ever higher compactness and power density. However, despite extensive theoretical efforts in recent years, experimental measurements remain scarce especially due to the critical challenges of preparing single-crystalline twisted interfaces and probing interfacial thermal transport with sufficient resolution. Here, we exploited the intrinsic twisted interfaces in highly oriented pyrolytic graphite (HOPG). By developing novel experimental schemes based on microfabricated mesas, we managed to achieve simultaneous mechanical characterizations and thermal measurements. In particular, we pushed the HOPG mesas with a microprobe to identify and rotate single-crystalline intrinsic interfaces owing to their slippery nature as is well known in structural superlubricity. Remarkably, we observed over 30-fold suppression of thermal conductance for the slippery interfaces by using epitaxial graphite as a control. Nonetheless, the interfacial conductance remains around 600 $\mathrm{MWm^{-2}K^{-1}}$ which surpasses the highest values for artificially stacked vdW structures by more than five times. Further, atomic simulations revealed the predominant role of the transverse acoustic phonons. Together, our findings highlight a general physical picture that directly correlates interfacial thermal transport with sliding resistance, and lay the foundation for twist-enabled thermal management which are particularly beneficial to twistronics and slidetronics.