Evidence for trivial Berry phase and absence of chiral anomaly in semimetal NbP

TL;DR

This study investigates the magneto-transport properties of NbP, revealing large non-saturating magnetoresistance, trivial Berry phase, and absence of chiral anomaly, challenging expectations for Weyl semimetals.

Contribution

It provides detailed experimental evidence showing NbP lacks chiral anomaly and has trivial Berry phase, contrasting with other Weyl semimetals.

Findings

Large non-saturating linear magnetoresistance linked to charge mobility fluctuations

Absence of negative longitudinal magnetoresistance indicating no chiral anomaly

Trivial Berry phase observed at high magnetic fields

Abstract

We report a detailed magneto-transport study in single crystals of NbP. High quality crystals were grown by vapour transport method. An exceptionally large magnetoresistance is confirmed at low temperature which is non-saturating and is linear at high fields. Models explaining the linear magnetoresistance are discussed and it is argued that in NbP this is linked to charge carrier mobility fluctuations. Negative longitudinal magnetoresistance is not seen, unlike several other Weyl monopnictides, suggesting lack of well defined chiral anomaly in NbP. Unambiguous Shubnikov-de-Haas oscillations are observed at low temperatures that are correlated to Berry phases. The Landau fan diagram indicates trivial Berry phase in NbP crystals corresponding to Fermi surface extrema at 30.5 Tesla.