Spin-orbit control of Dirac points and end states in inverted gap nanowires

TL;DR

This paper predicts that applying a transverse electric field to InAs/GaSb nanowires with inverted band structure can induce a topological phase transition, characterized by the emergence and disappearance of Dirac points and end states, revealing a spin-orbit controlled topological switch.

Contribution

It introduces a self-consistent k.p and BHZ model analysis showing how electric fields control Dirac points and topological phases in nanowires with inverted gaps, highlighting a spin-orbit driven transition.

Findings

Electric field causes collapse of the hybridization gap and induces a semimetal phase.

Massless Dirac points emerge from cancellation of kinetic and spin-orbit couplings.

End states exist up to a critical field and then vanish, indicating a topological transition.

Abstract

We predict that in InAs/GaSb nanowires with an inverted band alignment a transverse electric field induces a collapse of the hybridization gap, and a semimetal phase occurs. We use a self-consistent k.p approach and an adapted Bernevig-Hughes-Zhang model to show that massless Dirac points result from exact cancellation between the kinetic electron-hole coupling and the field-controlled spin-orbit coupling. End states - mid-gap states localized at the extremes of a finite nanowire - are supported up to a critical field, but suddenly fade away as the system is driven through the semimetal phase, eventually evolving to trivial surface states, which expose a spin-orbit induced topological transition to the normal phase.