Unique Dirac and Triple point fermiology in simple transition metals and their binary alloys

TL;DR

This paper reveals Dirac-like surface states and Fermi arc topologies in noble metals Ru, Re, and Os, linking these features to transport anomalies and demonstrating tunability via alloying.

Contribution

It uncovers the presence of Dirac-like excitations in simple transition metals and their alloys, expanding the understanding of topological surface states in elemental metals.

Findings

Dirac-like surface states identified in Ru, Re, Os

Fermi arcs consistent with experimental results

Alloying can tune excitations to three-component fermions

Abstract

Noble metal surfaces (Au, Ag and Cu etc.) have been extensively studied for the Shockley type surface states (SSs). Very recently, some of these Shockley SSs have been understood from the topological consideration, with the knowledge of global properties of electronic structure. In this letter, we show the existence of Dirac like excitations in the elemental noble metal Ru, Re and Os based on symmetry analysis and first principle calculations. The unique SSs driven Fermi arcs have been investigated in details for these metals. Our calculated SSs and Fermi arcs are consistent with the previous transport and photo-emission results. We attribute these Dirac excitation mediated Fermi arc topology to be the possible reasons behind several existing transport anomalies, such as large non-saturating magneto resistance, anomalous Nernst electromotive force and its giant oscillations, magnetic breakdown etc. We further show that the Dirac like excitations in these elemental metal can further be tuned to three component Fermionic excitations, using symmetry allowed alloy mechanism.