# Quantum limit transport and destruction of the Weyl nodes in TaAs

## TL;DR

This study explores the behavior of Weyl fermions in the semimetal TaAs under extremely high magnetic fields, revealing the destruction of Weyl nodes and the emergence of new correlated states at the quantum limit.

## Contribution

It demonstrates the experimental realization of the quantum limit in TaAs and uncovers the destruction of Weyl nodes and formation of textured states at high magnetic fields.

## Key findings

- Resistivity remains constant up to 50 T, consistent with chiral anomaly.
- Resistivity increases two orders of magnitude above 50 T, indicating a gap opening.
- Ultrasonic attenuation suggests mesoscopic textured states above 80 T.

## Abstract

Weyl fermions are a new ingredient for correlated states of electronic matter. A key difficulty has been that real materials also contain non-Weyl quasiparticles, and disentangling the experimental signatures has proven challenging. We use magnetic fields up to 95 tesla to drive the Weyl semimetal TaAs far into its quantum limit (QL), where only the purely chiral 0th Landau levels (LLs) of the Weyl fermions are occupied. We find the electrical resistivity to be nearly independent of magnetic field up to 50 tesla: unusual for conventional metals but consistent with the chiral anomaly for Weyl fermions. Above 50 tesla we observe a two-order-of-magnitude increase in resistivity, indicating that a gap opens in the chiral LLs. Above 80 tesla we observe strong ultrasonic attenuation below 2 kelvin, suggesting a mesoscopically-textured state of matter. These results point the way to inducing new correlated states of matter in the QL of Weyl semimetals.