Strongly Interacting Holes in Ge/Si Nanowires

TL;DR

This paper investigates how strong Coulomb interactions and Rashba spin-orbit coupling in Ge/Si nanowires influence their electronic properties, with implications for Majorana bound states.

Contribution

It develops a microscopic model and a Luttinger liquid framework to analyze Coulomb effects in Ge/Si nanowires, highlighting their impact on correlation functions and magnetic field responses.

Findings

Coulomb interactions significantly alter nanowire properties.

Derived scaling exponents for correlation functions.

Analyzed magnetic field effects on partial gap formation.

Abstract

We consider holes confined to Ge/Si core/shell nanowires subject to strong Rashba spin-orbit interaction and screened Coulomb interaction. Such wires can, for instance, serve as host systems for Majorana bound states. Starting from a microscopic model, we find that the Coulomb interaction strongly influences the properties of experimentally realistic wires. To show this, a Luttinger liquid description is derived based on a renormalization group analysis. This description in turn allows to calculate the scaling exponents of various correlation functions as a function of the microscopic system parameters. It furthermore permits to investigate the effect of Coulomb interaction on a small magnetic field, which opens a strongly anisotropic partial gap.