Observation of Yamaji magic angles in bismuth surfaces

TL;DR

This paper reports the observation of Yamaji magic angles in bismuth surfaces, revealing coherent topological hinge state transport and a warped cylindrical Fermi surface through angle-dependent magnetoresistance measurements.

Contribution

It provides experimental evidence of Yamaji angles and coherent interlayer transport in bismuth nanowires, highlighting the role of topological hinge states.

Findings

Observation of Yamaji magic angles in bismuth nanowires

Detection of flat bands induced by magnetic fields

Evidence of coherent topological hinge state transport

Abstract

Bismuth consist of bismuth bilayers that are two-dimensional topological insulators and correspondingly, the surface is an array of edge states. Moreover, topological models, including second order topologic order, predict an interlayer electrical coupling mediated by hinge states. Here we report that angle dependent magnetoresistance measurements of small diameter single-crystal bismuth nanowires exhibit the sequence of magnetoresistance (MR) peaks at Yamaji magic angles and a peak for B//bilayer, indicating coherent transport between layers, and showing that the Fermi surface of surface electrons is a warped cylinder. The MR peaks are associated with magnetic field induced flat bands that are reminiscent of the well-known flat bands in bilayer graphene. Coherent transport across layers is interpreted in term of transport by topological hinge states.