Quantitative magneto-optical investigation of superconductor/ferromagnet hybrid structures

TL;DR

This study uses quantitative magneto-optical imaging to analyze superconductor/ferromagnet hybrid structures, revealing the superconductor's weaker magnetic response amidst larger magnetic fields from the ferromagnetic layer.

Contribution

It introduces comprehensive protocols for calibrating and converting magneto-optical data, enabling detailed analysis of superconductor/ferromagnet hybrid structures.

Findings

Magneto-optical imaging effectively distinguishes superconductor response from magnetic background.

The developed protocols improve accuracy in magnetic field mapping.

Superconductor response is weaker compared to ferromagnetic layers in hybrid structures.

Abstract

We present a detailed quantitative magneto-optical imaging study of several superconductor/ferromagnet hybrid structures, including Nb deposited on top of thermomagnetically patterned NdFeB, and permalloy/niobium with erasable and tailored magnetic landscapes imprinted in the permalloy layer. The magneto-optical imaging data is complemented with and compared to scanning Hall probe microscopy measurements. Comprehensive protocols have been developed for calibrating, testing, and converting Faraday rotation data to magnetic field maps. Applied to the acquired data, they reveal the comparatively weaker magnetic response of the superconductor from the background of larger fields and field gradients generated by the magnetic layer.