Phonon thermal transport in \b{eta}-NX (X=P, As, Sb) monolayers: a first-principles study of the interplay between harmonic and anharmonic phonon properties

TL;DR

This study uses first-principles calculations to analyze how harmonic and anharmonic phonon properties influence thermal conductivity in ta-NX monolayers (X=P, As, Sb), revealing key factors affecting heat transport in these 2D materials.

Contribution

It provides a detailed first-principles analysis of phonon transport in ta-NX monolayers, highlighting the interplay between harmonic and anharmonic effects on thermal conductivity.

Findings

ta-NSb has the highest thermal conductivity among the studied monolayers.

ta-NP exhibits the lowest thermal conductivity despite having the minimum atomic mass.

Higher phonon group velocities and lifetimes enhance thermal conductivity in these materials.

Abstract

The investigation of thermal properties of recently emerged two-dimensional (2D) materials is a necessary step towards fulfilling their potential applications in nano-electronics devices. In this study, the thermal conductivity of novel \b{eta}-NX (X=P, As, Sb) monolayers are investigated using a first-principles density functional theory (DFT) study based on the full solution of the linearized Peierls-Boltzmann transport equation (PBTE). The results show that the room temperature thermal conductivities of \b{eta}-NP, \b{eta}-NAs, and \b{eta}-NSb are about 1.1, 5.5, and 34.0 times higher than those of single-element \b{eta}-P, \b{eta}-As, and \b{eta}-Sb monolayers, respectively. The phonon transport analysis reveals that higher phonon group velocities as well as phonon lifetimes are responsible for such an enhancement in the lattice thermal conductivities of \b{eta}-NX (X=P, As, Sb) binary compounds compared to single-element group-VA monolayers. We found that \b{eta}-NP has the minimum thermal conductivity among \b{eta}-NX (X=P, As, Sb) monolayers, while it has the minimum average atomic mass, which is in contrast with the common assumption that lower mass systems exhibit higher thermal conductivities. This work demonstrates the trade-off between harmonic and anharmonic phonon properties in determining the variation of the thermal conductivity among \b{eta}-NX (X=P, As, Sb) monolayers. The higher anharmonicity in \b{eta}-NP is found to be responsible for the lower thermal conductivity of this monolayer.