Dirac State in a Centrosymmetric Superconductor alpha-PdBi2

TL;DR

This study investigates the electronic structure of alpha-PdBi2, a superconductor with potential topological properties, revealing Dirac states and surface Rashba states that could be relevant for topological quantum computing.

Contribution

It provides the first detailed ARPES analysis of alpha-PdBi2, identifying Dirac and Rashba states and linking electronic structure to topological superconductivity possibilities.

Findings

Dirac states located 1.26 eV below the chemical potential.

Multiple band crossings at the chemical potential.

Presence of surface Rashba states near the chemical potential.

Abstract

Topological superconductor (TSC) hosting Majorana fermions has been established as a milestone that may shift our scientific trajectory from research to applications in topological quantum computing. Recently, superconducting Pd-Bi binaries have attracted great attention as a possible medium for the TSC phase as a result of their large spin-orbit coupling strength. Here, we report a systematic high-resolution angle-resolved photoemission spectroscopy (ARPES) study on the normal state electronic structure of superconducting alpha-PdBi2 (Tc = 1.7 K). Our results show the presence of Dirac states at higher-binding energy with the location of the Dirac point at 1.26 eV below the chemical potential at the zone center. Furthermore, the ARPES data indicate multiple band crossings at the chemical potential, consistent with the metallic behavior of alpha-PdBi2. Our detailed experimental studies are complemented by first-principles calculations, which reveal the presence of surface Rashba states residing in the vicinity of the chemical potential. The obtained results provide an opportunity to investigate the relationship between superconductivity and topology, as well as explore pathways to possible future platforms for topological quantum computing.