Observation of the spin-polarized surface state in a noncentrosymmetric superconductor BiPd

TL;DR

This study uses ARPES techniques to identify spin-polarized surface states in BiPd, revealing their energy position and spin properties, which are crucial for understanding topological superconductivity in this material.

Contribution

It provides the first detailed experimental characterization of spin-polarized surface states in BiPd, clarifying their energy location and implications for topological superconductivity.

Findings

Surface state at ~700 meV below Fermi level with Dirac point.

Presence of spin polarization in surface states.

Absence of spin-polarized states near Fermi level.

Abstract

Recently, noncentrosymmetric superconductor BiPd has attracted considerable research interest due to the possibility of hosting topological superconductivity. Here we report a systematic high-resolution angle-resolved photoemission spectroscopy (ARPES) and spin-resolved ARPES study of the normal state electronic and spin properties of BiPd. Our experimental results show the presence of a surface state at higher-binding energy with the location of Dirac point at around 700 meV below the Fermi level. The detailed photon energy, temperature-dependent and spin-resolved ARPES measurements complemented by our first principles calculations demonstrate the existence of the spin polarized surface states at high-binding energy. The absence of such spin-polarized surface states near the Fermi level negates the possibility of a topological superconducting behavior on the surface. Our direct experimental observation of spin-polarized surface states in BiPd provides critical information that will guide the future search for topological superconductivity in noncentrosymmetric materials.