ZrOsSi: A $Z_2$ topological metal with a superconducting ground state

TL;DR

This paper investigates ZrOsSi, revealing it as a $Z_2$ topological metal with surface Dirac cones, and explores its potential for topological superconductivity through combined experimental and theoretical methods.

Contribution

It provides the first detailed analysis of ZrOsSi's topological properties, combining NMR measurements and first-principles calculations to identify its topological metallic state.

Findings

ZrOsSi is a $Z_2$ topological metal with surface Dirac cones.

Replacing Ta/Nb with Zr expands the lattice and shifts the material towards an insulator.

ZrOsSi exhibits properties similar to a doped strong topological insulator.

Abstract

The silicide superconductors (Ta, Nb, Zr)OsSi are among the best candidate materials for investigating the interplay of topological order and superconductivity. Here, we investigate in detail the normal-state topological properties of (Ta, Nb, Zr)OsSi, focusing on ZrOsSi, by employing a combination of $^{29}$Si nuclear magnetic resonance (NMR) measurements and first-principles band-structure calculations. We show that, while (Ta, Nb)OsSi behave as almost ideal metals, characterized by weak electronic correlations and a relatively low density of states, the replacement of Ta (or Nb) with Zr expands the crystal lattice and shifts ZrOsSi towards an insulator. Our ab initio calculations indicate that ZrOsSi is a $Z_2$ topological metal with clear surface Dirac cones and properties similar to a doped strong topological insulator.