Observation of open Fermi surface in bismuth

TL;DR

This study reveals that bismuth nanowires exhibit an open Fermi surface with coherent interlayer transport, highlighting the importance of hinge channels and layered structure in its electronic properties.

Contribution

The paper provides direct experimental evidence of an open Fermi surface in bismuth and characterizes the interlayer coherence and transfer integral in nanowires.

Findings

Observation of Yamaji magic angle peaks indicating flat bands.

Detection of a high-field peak confirming interlayer coherence.

Demonstration of an extended open Fermi surface for holes.

Abstract

Bismuth is a candidate material for three dimensional higher dimensional topological insulators. We performed electronic transport experiments on small diameter crystalline bismuth nanowires to clarify the role of the proposed hinge channels in the interlayer coupling. The magnetoresistance presents a sequence of peaks at Yamaji magic angles for which the interlayer group velocity is zero pointing to flat bands due to the layered structure. Furthermore, we observe a peak for high magnetic fields applied parallel to the layers, a definitive signature of interlayer coherence that enables deduction of the interlayer transfer integral of 8 meV. We demonstrate transport by a corrugated open Fermi surface of holes that is extended, with the high angular precision of around 0.016 rad in the interlayer direction. The observations indicate that coherence and the crystallographic direction set by hinges play a key role in the interlayer coupling of bismuth.