Effect of uniaxial stress on the electronic band structure of NbP

TL;DR

This study investigates how uniaxial stress affects the electronic band structure of NbP, revealing that strain can lift Fermi-surface degeneracies and shift Weyl points, enabling Fermi level tuning.

Contribution

It combines experimental Shubnikov-de Haas measurements with advanced band structure calculations to show strain-induced effects in NbP's electronic properties.

Findings

Uniaxial stress causes splitting of Fermi-surface frequencies.

Calculated and experimental frequencies show qualitative agreement.

Weyl points can be shifted significantly with only 0.8% strain.

Abstract

The Weyl semimetal NbP exhibits a very small Fermi surface consisting of two electron and two hole pockets, whose fourfold degeneracy in $k$ space is tied to the rotational symmetry of the underlying tetragonal crystal lattice. By applying uniaxial stress, the crystal symmetry can be reduced, which successively leads to a degeneracy lifting of the Fermi-surface pockets. This is reflected by a splitting of the Shubnikov-de Haas frequencies when the magnetic field is aligned along the $c$ axis of the tetragonal lattice. In this study, we present the measurement of Shubnikov-de Haas oscillations of single-crystalline NbP samples under uniaxial tension, combined with state-of-the-art calculations of the electronic band structure. Our results show qualitative agreement between calculated and experimentally determined Shubnikov-de Haas frequencies, demonstrating the robustness of the band-structure calculations upon introducing strain. Furthermore, we predict a significant shift of the Weyl points with increasing uniaxial tension, allowing for an effective tuning to the Fermi level at only 0.8% of strain along the $a$ axis.