Effects of the electrostatic environment on the Majorana nanowire devices

TL;DR

This paper investigates how electrostatic interactions influence Majorana nanowire devices, revealing that Coulomb effects affect topological phase boundaries and energy oscillations, with implications for experimental comparisons.

Contribution

It introduces the role of electrostatic interactions in Majorana nanowire devices, showing their impact on phase boundaries and energy oscillations, which was previously overlooked.

Findings

Coulomb interaction causes the chemical potential to respond to magnetic fields.

Screening by the superconductor suppresses electrostatic effects.

Inverse self-capacitance captures electrostatic and Zeeman interplay in single-electron modes.

Abstract

One of the promising platforms for creating Majorana bound states is a hybrid nanostructure consisting of a semiconducting nanowire covered by a superconductor. We analyze the previously disregarded role of electrostatic interaction in these devices. Our main result is that Coulomb interaction causes the chemical potential to respond to an applied magnetic field, while spin-orbit interaction and screening by the superconducting lead suppress this response. Consequently, the electrostatic environment influences two properties of Majorana devices: the shape of the topological phase boundary and the oscillations of the Majorana splitting energy. We demonstrate that both properties show a non-universal behavior, and depend on the details of the electrostatic environment. We show that when the wire only contains a single electron mode, the experimentally accessible inverse self-capacitance of this mode fully captures the interplay between electrostatics and Zeeman field. This offers a way to compare theoretical predictions with experiments.