Revealing Fano Resonance in Dirac Materials ZrTe5 through Raman Scattering

TL;DR

This study uncovers Fano resonance in ZrTe5 through Raman scattering, revealing specific phonon-electron interactions and their temperature dependence, advancing understanding of electron-phonon coupling in Dirac materials.

Contribution

It demonstrates the selective Fano resonance in B2g I phonon mode of ZrTe5 and links it to electron-phonon coupling and temperature effects, using experimental and first-principles methods.

Findings

Fano resonance observed only in B2g I mode

Enhanced Fano asymmetry at higher temperatures

Quantum interference between phonons and electronic excitations

Abstract

We explore the Fano resonance in ZrTe5, using Raman scattering measurements. We identified two closely spaced B2g phonon modes, B2g I and B2g II, around 9 meV and 10 meV, respectively. Interestingly, only B2g I exhibited the Fano resonance, an outcome of quantum interference between discrete phonon modes and continuous electronic excitations. This is consistent with the much stronger electron-phonon coupling of B2g I mode demonstrated by first-principles calculations. Additionally, temperature-dependent measurements highlight an enhanced Fano asymmetry at elevated temperatures, contributed by the thermal renormalization of the band structure and electron-phonon coupling. This study offers insights into the complex interrelation of electron-phonon coupling, thermal effects, and Fano resonances in ZrTe5.