Proximity-induced density-of-states oscillations in a superconductor/strong-ferromagnet system

TL;DR

This study investigates how the tunneling density of states in superconductor/strong-ferromagnet bilayers oscillates with increasing ferromagnet thickness, revealing multiple proximity-induced oscillations and sign changes in the DOS.

Contribution

It provides experimental evidence of multiple DOS oscillations and sign inversions in superconductor/strong-ferromagnet bilayers as a function of ferromagnet thickness.

Findings

Multiple DOS oscillations observed with increasing Ni thickness.

Sign inversion of DOS features occurs twice between 1 and 5 nm Ni.

Proximity effect induces oscillatory behavior in the superconductor/ferromagnet system.

Abstract

We have measured the evolution of the tunneling density of states (DOS) in superconductor/ferromagnet (S/F) bilayers with increasing F-layer thickness, where F in our experiment is the strong ferromagnet Ni. As a function of increasing Ni thickness, we detect multiple oscillations in the DOS at the Fermi energy from differential conductance measurements. The features in the DOS associated with the proximity effect change from normal to inverted twice as the Ni thickness increases from 1 to 5 nm.