Topological diffusive metal in amorphous transition metal monosilicides

TL;DR

This paper demonstrates that topological multifold fermions can persist in amorphous transition metal monosilicides, transforming into a diffusive metal phase, and introduces the spectral localizer as a tool to detect these properties.

Contribution

It provides the first theoretical evidence that topological properties survive in amorphous metals and introduces the spectral localizer for real-space topological characterization.

Findings

Topological multifold fermions persist in amorphous transition metal monosilicides.

A diffusive metal phase retains topological features despite structural disorder.

The spectral localizer effectively signals the presence of multifold fermions in disordered systems.

Abstract

In chiral crystals crystalline symmetries can protect multifold fermions, pseudo-relativistic masless quasiparticles that have no high-energy counterparts. Their realization in transition metal monosilicides has exemplified their intriguing physical properties, such as long Fermi arc surface states and unusual optical responses. Recent experimental studies on amorphous transition metal monosilicides suggest that topological properties may survive beyond crystals, even though theoretical evidence is lacking. Motivated by these findings, we theoretically study a tight-binding model of amorphous transition metal monosilicides. We find that topological properties of multifold fermions survive in the presence of structural disorder that converts the semimetal into a diffusive metal. We characterize this topological diffusive metal phase with the spectral localizer, a real-space topological indicator that we show can signal multifold fermions. Our findings showcase how topological properties can survive in disordered metals, and how they can be uncovered using the spectral localizer.