Geometrically Enhanced Quantum Oscillatory Signal and Nonzero Berry's Phase in Indium Arsenide Surface

TL;DR

This paper introduces a geometric method using a metal shunt to enhance surface quantum oscillations in indium arsenide, enabling clearer detection of Berry's phase and spin-orbit interactions without doping.

Contribution

A novel non-intrusive geometric approach is proposed to isolate surface signals in InAs, improving detection of quantum oscillations and Berry's phase.

Findings

Clear quantum oscillations observed at InAs surface

Nonzero Berry's phase detected in InAs surface

Large Rashba spin-orbit coupling identified (~1 eV·A)

Abstract

In a system accommodating both surface and bulk conduction channels, a long-standing challenge is to extract weak Shubnikov-de Haas oscillation signal in the surface from a large background stemming from the bulk. Conventional methods to suppress the bulk conduction often involve doping, an intrusive approach, to reduce the bulk carrier density. Here we propose a geometric method, i.e. attaching a metal shunt to the indium arsenide epilayer, to redistribute current and thus enhance the oscillation-to-background ratio. This allows us, for the first time, to observe clear quantum oscillations and nonzero Berry's phase at the surface of indium arsenide. We also identify the existence of a Rashba type spin-orbit interaction, on the InAs surface, with a large coupling constant ~ 1 eVA. We anticipate wide applicability of this non-intrusive architecture in similar systems such as topological insulators.