Photoinduced renormalization of Dirac states in BaNiS$_2$

TL;DR

This study demonstrates that ultrafast photoexcitation can significantly reduce the Fermi velocity of Dirac states in BaNiS$_2$, driven by enhanced screening and non-local electron correlations, revealing a new way to manipulate electronic properties.

Contribution

It provides experimental evidence and theoretical insight into photoinduced band renormalization in a Dirac semimetal, highlighting the role of non-local correlations in electronic structure control.

Findings

Reduction of Fermi velocity in Dirac bands upon photoexcitation

Photoinduced enhancement of screening alters electron correlations

Non-rigid band shifts observed at the Brillouin zone center

Abstract

By means of pump-probe time- and angle-resolved photoelectron spectroscopy, we provide evidence of a sizeable reduction of the Fermi velocity of out-of-equilibrium Dirac bands in the quasi-two-dimensional semimetal BaNiS$_2$. First-principle calculations indicate that this band renormalization is ascribed to a change in non-local electron correlations driven by a photo-induced enhancement of screening properties. This effect is accompanied by a slowing down of the Dirac fermions and by a non-rigid shift of the bands at the center of the Brillouin zone. This result suggests that other similar electronic structure renormalizations may be photoinduced in other materials in presence of strong non-local correlations.