Scanning Tunneling Spectroscopy of the superconducting proximity effect in a diluted ferromagnetic alloy

TL;DR

This study investigates the superconducting proximity effect in a Nb/CuNi bilayer using low-temperature scanning tunneling spectroscopy, revealing the importance of spin relaxation mechanisms in modeling the local density of states.

Contribution

It introduces a detailed experimental analysis of the proximity effect in a ferromagnetic alloy and incorporates spin relaxation effects into the Usadel equations for better data description.

Findings

High homogeneity of measured spectra.

Necessity of including spin relaxation in theoretical models.

Good agreement between modified theory and experimental data.

Abstract

We studied the proximity effect between a superconductor (Nb) and a diluted ferromagnetic alloy (CuNi) in a bilayer geometry. We measured the local density of states on top of the ferromagnetic layer, which thickness varies on each sample, with a very low temperature Scanning Tunneling Microscope. The measured spectra display a very high homogeneity. The analysis of the experimental data shows the need to take into account an additional scattering mechanism. By including in the Usadel equations the effect of the spin relaxation in the ferromagnetic alloy, we obtain a good description of the experimental data.