Room-temperature chiral charge pumping in Dirac semimetals

TL;DR

This paper demonstrates room-temperature chiral charge pumping and valley polarization diffusion in Dirac semimetals, revealing new experimental signatures of the chiral anomaly beyond traditional low-temperature magnetoresistance measurements.

Contribution

It introduces novel experimental methods to observe and analyze chiral anomaly effects at room temperature in Dirac semimetals, expanding understanding of topological semimetals.

Findings

Observation of nonlocal response with negative field dependence at room temperature

Detection of a large magneto-optic Kerr effect induced by parallel electric and magnetic fields

Quantitative analysis of chiral anomaly phenomena in Dirac semimetals

Abstract

Chiral anomaly, a non-conservation of chiral charge pumped by the topological nontrivial gauge fields, has been predicted to exist in Weyl semimetals. However, until now, the experimental signature of this effect exclusively relies on the observation of negative longitudinal magnetoresistance at low temperatures. Here, we report the field-modulated chiral charge pumping process and valley diffusion in Cd3As2. Apart from the conventional negative magnetoresistance, we observe an unusual nonlocal response with negative field dependence up to room temperature, originating from the diffusion of valley polarization. Furthermore, a large magneto-optic Kerr effect generated by parallel electric and magnetic fields is detected. These new experimental approaches provide a quantitative analysis of the chiral anomaly phenomenon which is inaccessible previously. The ability to manipulate the valley polarization in topological semimetal at room temperature opens up a brand-new route towards understanding its fundamental properties and utilizing the chiral fermions.