Specific Heat of Twisted Bilayer Graphene

TL;DR

This study investigates how twisting bilayer graphene affects its phonon specific heat, revealing unique temperature dependencies and suggesting potential for thermal property engineering through twisting.

Contribution

It introduces a detailed analysis of phonon specific heat in twisted bilayer graphene, highlighting the influence of twist angle on thermal properties at low temperatures.

Findings

Specific heat varies as T^n with n=1, 1.6, 1.3 for graphene, bilayer, and twisted bilayer.

Twist angle significantly affects phonon specific heat at low temperatures.

Results indicate potential for phonon-based thermal property control in layered materials.

Abstract

We have studied the phonon specific heat in single-layer, bilayer and twisted bilayer graphene. The calculations were performed using the Born-von Karman model of lattice dynamics for intralayer atomic interactions and spherically symmetric interatomic potential for interlayer interactions. We found that at temperature T<15 K, specific heat varies with temperature as T^n, where n = 1 for graphene, n = 1.6 for bilayer graphene and n = 1.3 for the twisted bilayer graphene. The phonon specific heat reveals an intriguing dependence on the twist angle in bilayer graphene, which is particularly pronounced at low temperature. The results suggest a possibility of phonon engineering of thermal properties of layered materials by twisting the atomic planes.