Signature of chiral fermion instability in the Weyl semimetal TaAs above the quantum limit

TL;DR

This study investigates the electrical transport in Weyl semimetal TaAs under high magnetic fields, revealing anomalies linked to electron-hole pairing instability when electrons are confined to the lowest Landau level.

Contribution

It provides experimental evidence of chiral fermion instability in TaAs above the quantum limit, highlighting electron-electron interactions in topological semimetals.

Findings

Anomalies in magnetoresistance and Hall signals at ultra-low temperatures.

Temperature-dependent electron-hole pairing instability.

TaAs as a platform for studying interactions in topological semimetals.

Abstract

We report the electrical transport properties for Weyl semimetal TaAs in an intense magnetic field. Series of anomalies occur in the longitudinal magnetoresistance and Hall signals at ultra-low temperatures when the Weyl electrons are confined into the lowest Landau level. These strongly temperature-dependent anomalies are ascribed to the electron-hole pairing instability. Our measurements show that the Weyl semimetal TaAs in the ultraquantum regime provides a good platform for studying electron-electron interaction in topological nontrivial semimetals.