Spin-polarized transport and quantum phase transitions in one-dimensional superconductor-ferromagnetic insulator heterostructures

TL;DR

This paper proposes a one-dimensional hybrid nanostructure device that enables the study of quantum phase transitions through transport measurements, focusing on spin-polarized Andreev bound states and controllable inhomogeneous Zeeman interactions.

Contribution

It introduces a novel hybrid nanowire device with a shorter ferromagnetic insulator layer and minimal Rashba interaction to explore tunable quantum phase transitions via transport signatures.

Findings

Device can be tuned across spin- and fermion parity-changing QPTs.

Zero-energy crossings of subgap ABS indicate quantum phase transitions.

Experimental feasibility for studying QPTs in hybrid nanowires.

Abstract

We theoretically propose a one-dimensional electronic nanodevice inspired in recently fabricated semiconductor-superconductor-ferromagnetic insulator (SE-SC-FMI) hybrid heterostructures, and investigate its zero-temperature transport properties. While previous related studies have primarily focused on the potential for generating topological superconductors hosting Majorana fermions, we propose an alternative application: using these hybrids to explore controllable quantum phase transitions (QPTs) detectable through transport measurements. Our study highlights two key differences from existing devices: first, the length of the FMI layer is shorter than that of the SE-SC heterostructure, introducing an inhomogeneous Zeeman interaction with significant effects on the induced Andreev bound states (ABS). Second, we focus on semiconductor nanowires with minimal or no Rashba spin-orbit interaction, allowing for the induction of spin-polarized ABS and high-spin quantum ground states. We show that the device can be tuned across spin- and fermion parity-changing QPTs by adjusting the FMI layer length orange and/or by applying a global backgate voltage, with zero-energy crossings of subgap ABS as signatures of these transitions. Our findings suggest that these effects are experimentally accessible and offer a robust platform for studying quantum phase transitions in hybrid nanowires.