Andreev reflection enhanced single hole tunneling in Ge/Si core/shell nanowire quantum dot

TL;DR

This study investigates how Andreev reflection enhances single hole tunneling in Ge/Si core/shell nanowire quantum dots, revealing zero field magnetoconductance peaks linked to phase coherent tunneling, suppressed by magnetic fields.

Contribution

It provides experimental evidence of Andreev reflection enhancing hole tunneling in Ge/Si nanowire quantum dots, a novel observation in this material system.

Findings

Observation of zero field magnetoconductance peaks.

Evidence of Andreev reflection enhancing tunneling.

Magnetic field suppresses the peaks without destroying superconductivity.

Abstract

We experimentally study the electrical transport properties of Ge/Si core/shell nanowire device with two superconducting leads in the Coulomb blockade regime. Anomalous zero field magnetoconductance peaks are observed for the first time at the gate voltages where Coulomb blockade oscillation peaks present. Many evidences indicate this feature is due to Andreev reflection enhanced phase coherent single hole tunneling through the quantum dot, which can be suppressed by an external magnetic field without destroying the superconducting states in the electrodes.