Light-induced renormalization of the band structure of chiral tellurium

TL;DR

This study demonstrates how near-infrared light can dynamically modify the electronic band structure of chiral tellurium through coherent phonon excitation, revealing a pathway for light-induced topological phase transitions.

Contribution

It provides the first direct observation of light-induced band structure renormalization in chiral tellurium using time-resolved photoelectron spectroscopy and theoretical modeling.

Findings

Coherent phonons modulate the Peierls gap upon photoexcitation.

Band edges oscillate in phase due to phonon-induced Hubbard U modulation.

Evidence of light-driven topological phase transition potential.

Abstract

Chirality in tellurium derives from a Peierls distortion driven by strong electron-phonon coupling, making this material a unique candidate for observing a light-induced topological phase transition. By using time- and angle-resolved photoelectron spectroscopy (trARPES), we reveal that upon near-infrared photoexcitation the Peierls gap is modulated by displacively excited coherent phonons with $\mathrm{A_{1g}}$ symmetry as well as chiral-symmetry-breaking $\mathrm{E'_{LO}}$ modes. By comparison with state-of-the-art TDDFT+U calculations, we reveal the microscopic origin of the in-phase oscillations of band edges, due to phonon-induced modulation of the effective Hubbard $U$ term.