Electronic properties of topological insulator candidate CaAgAs

TL;DR

This study investigates the electronic structure of CaAgAs, a topological insulator candidate, using ARPES, calculations, and transport measurements, revealing its potential for topological phenomena near the Fermi level.

Contribution

The paper provides combined experimental and theoretical analysis of CaAgAs, demonstrating its topological properties and electronic structure near the Fermi level.

Findings

Bulk valence band crosses Fermi level at gamma-point

Band dispersion matches calculations with Fermi level shifted by -0.5 eV

Transport measurements show abundant p-type carriers

Abstract

The topological phases of matter provide the opportunity to observe many exotic properties, like the existence of two dimensional topological surface states in the form of Dirac cone in topological insulators, chiral transport through open Fermi arc in Weyl semimetals etc. However, these properties can only affect the transport characteristics and therefore can be useful for applications only if the topological phenomena occur near the Fermi level. CaAgAs is a promising candidate, wherein the ab-initio calculations predict line-node at the Fermi level which on including spin-orbit coupling transforms into a topological insulator. In this report, we study the electronic structure of CaAgAs with angle resolved photoemission spectroscopy (ARPES), ab-initio calculations and transport measurements. The ARPES results show that the bulk valence band crosses the Fermi energy at gamma-point and the band dispersion matches the ab-initio calculations closely on shifting the Fermi energy by -0.5 eV. ARPES results are in good agreement with our transport measurements which show abundant p-type carriers.