Phase controlled superconducting proximity effect probed by tunneling spectroscopy

TL;DR

This study uses ultra-low temperature tunneling spectroscopy with a dual-mode STM-AFM to investigate how the superconducting proximity effect in normal wires varies with phase difference, revealing phase-dependent minigap behavior.

Contribution

It demonstrates phase-controlled minigap formation in normal wires connected to superconductors, supported by experimental data and quasiclassical theory modeling.

Findings

Minigap develops uniformly in the normal wire and near interfaces.

Minigap size varies periodically with phase difference.

Quasiclassical theory accurately models the observed phenomena.

Abstract

Using a dual-mode STM-AFM microscope operating below 50mK we measured the Local Density of States (LDoS) along small normal wires connected at both ends to superconductors with different phases. We observe that a uniform minigap can develop in the whole normal wire and in the superconductors near the interfaces. The minigap depends periodically on the phase difference. The quasiclassical theory of superconductivity applied to a simplified 1D model geometry accounts well for the data.