Anomalous Nernst effect and field-induced Lifshitz transition in Weyl semimetals TaP and TaAs

TL;DR

This paper demonstrates that the giant anomalous Nernst effect in Weyl semimetals TaP and TaAs serves as a clear bulk signature of Weyl physics, linked to Berry curvature from Weyl points, and reveals a field-induced Lifshitz transition.

Contribution

It introduces the anomalous Nernst effect as a new bulk probe for Weyl fermions and characterizes the field-induced Lifshitz transition in TaP and TaAs.

Findings

Giant anomalous Nernst signal observed in TaP and TaAs

Saturation plateau in Nernst response beyond a critical magnetic field

Field-induced Lifshitz transition linked to Weyl points

Abstract

The discovery of Weyl fermions in transition metal monoarsenides/phosphides without inversion symmetry represents an exceptional breakthrough in modern condensed matter physics. However, exploring the inherent nature of these quasiparticles is experimentally elusive because most of the experimental probes rely on analysing Fermi arc topology or controversial signatures such as the appearance of the chiral anomaly and the giant magnetoresistance. Here we show that the prototypical type-I Weyl semimetals TaP and TaAs possess a giant anomalous Nernst signal with a characteristic saturation plateau beyond a critical field which can be understood as a direct consequence of the finite Berry curvature originating from the Weyl points. Our results thus promote the Nernst coefficient as an ideal bulk probe for detecting and exploring the fingerprints of emergent Weyl physics.