Quantum transport in a compensated semimetal W2As3 with nontrivial Z2 indices

TL;DR

This study identifies W2As3 as a topological semimetal with nontrivial Z2 indices, exhibiting electron-hole compensation, multiband transport, and topological surface states, confirmed through first-principles calculations and magnetotransport experiments.

Contribution

It provides the first comprehensive experimental and theoretical investigation of W2As3's topological properties and transport behavior.

Findings

W2As3 has nontrivial Z2 topological indices [1;111].

The material exhibits nearly quadratic magnetoresistance up to 15 T.

Multiband features and a nontrivial Berry's phase are observed.

Abstract

We report a topological semimetal W2As3 with a space group C2/m. Based on the first-principles calculations, band crossings are partially gapped when spin-orbit coupling is included. The Z2 indices at the electron filling are [1;111], characterizing a strong topological insulator and topological surface states. From the magnetotransport measurements, nearly quadratic field dependence of magnetoresistance (MR) (B || [200]) at 3 K indicates an electron-hole compensated compound whose longitudinal MR reaches 115 at 3 K and 15 T. In addition, multiband features are detected from the high-magnetic-field Shubnikov-de Haas (SdH) oscillation, Hall resistivity, and band calculations. A nontrivial pi Berry's phase is obtained, suggesting the topological feature of this material. A two- band model can fit well the conductivity and Hall coefficient. Our experiments manifest that the transport properties of W2As3 are in good agreement with the theoretical calculations.