Phonon-Mediated Quasiparticle Lifetime Renormalizations in Few-Layer Hexagonal Boron Nitride

TL;DR

This paper reveals a phonon-mediated quasiparticle lifetime renormalization in few-layer hexagonal boron nitride, showing a significant electron mass enhancement affecting $\pi$-band states, with implications for device applications.

Contribution

It uncovers a previously unknown many-body state in wide-bandgap insulators like hBN, driven by phonon interactions affecting quasiparticle lifetimes.

Findings

Large electron mass enhancement in few-layer hBN

Renormalization is phonon-mediated and involves multiple phonons

Implications for hBN-based device performance

Abstract

Understanding the collective behavior of the quasiparticles in solid-state systems underpins the field of non-volatile electronics, including the opportunity to control many-body effects for well-desired physical phenomena and their applications. Hexagonal boron nitride (hBN) is a wide energy bandgap semiconductor, showing immense potential as a platform for low-dimensional device heterostructures. It is an inert dielectric used for gated devices, having a negligible orbital hybridization when placed in contact with other systems. Despite its inertness, we discover a large electron mass enhancement in few-layer hBN affecting the lifetime of the $\pi$-band states. We show that the renormalization is phonon-mediated and consistent with both single- and multiple-phonon scattering events. Our findings thus unveil a so-far unknown many-body state in a wide-bandgap insulator, having important implications for devices using hBN as one of their building blocks.