Superconductor-Nanowire Devices from Tunneling to the Multichannel Regime: Zero-Bias Oscillations and Magnetoconductance Crossover

TL;DR

This study investigates superconductor-nanowire devices, revealing zero-bias oscillations and a conductance crossover influenced by magnetic field and gate voltage, with implications for Majorana modes and other phenomena.

Contribution

It provides new insights into the transport behavior and conductance crossover in superconductor-nanowire devices, exploring the roles of magnetic field, gate voltage, and potential Majorana zero modes.

Findings

Zero-bias features oscillate with magnetic field and gate voltage.

Magnetoconductance shows a crossover at ~0.5 T between tunneling and multichannel regimes.

Conductance is enhanced or suppressed depending on the regime and magnetic field.

Abstract

We present transport measurements in superconductor-nanowire devices with a gated constriction forming a quantum point contact. Zero-bias features in tunneling spectroscopy appear at finite magnetic fields, and oscillate in amplitude and split away from zero bias as a function of magnetic field and gate voltage. A crossover in magnetoconductance is observed: Magnetic fields above ~ 0.5 T enhance conductance in the low-conductance (tunneling) regime but suppress conductance in the high-conductance (multichannel) regime. We consider these results in the context of Majorana zero modes as well as alternatives, including Kondo effect and analogs of 0.7 structure in a disordered nanowire.