Direct Observation of Nonequivalent Fermi-Arc States of Opposite Surfaces in Noncentrosymmetric Weyl Semimetal NbP

TL;DR

This study uses ARPES to observe distinct Fermi-arc states on opposite surfaces of NbP, revealing surface-dependent electronic structures in a Weyl semimetal, which could lead to novel quantum phenomena.

Contribution

First direct observation of nonequivalent Fermi-arc states on opposite surfaces of a noncentrosymmetric Weyl semimetal NbP, highlighting surface-dependent electronic topology.

Findings

Significant difference in Fermi-surface topology between surfaces

Fermi arcs on both surfaces connect to the same bulk Weyl nodes

Discrepancy between theoretical predictions and experimental surface electronic structures

Abstract

We have performed high-resolution angle-resolved photoemission spectroscopy (ARPES) on noncentrosymmetric Weyl semimetal candidate NbP, and determined the electronic states of both Nb- and P-terminated surfaces corresponding to the "opposite" surfaces of a polar crystal. We revealed a drastic difference in the Fermi-surface topology between the opposite surfaces, whereas the Fermi arcs on both surfaces are likely terminated at the surface projection of the same bulk Weyl nodes. Comparison of the ARPES data with our first-principles band calculations suggests notable difference in electronic structure at the Nb-terminated surface between theory and experiment. The present result opens a platform for realizing exotic quantum phenomena arising from unusual surface properties of Weyl semimetals.