Magnetization reversal in Py/Gd heterostructures

TL;DR

This study investigates the magnetic behavior of Py/Gd heterostructures using magnetometry and transport techniques, revealing a spin-flop transition, temperature-dependent magnetoresistance sign change, and non-collinear magnetization configurations.

Contribution

It provides new insights into the magnetic interactions and configurations in Py/Gd heterostructures, including the role of structural inhomogeneity and exchange-spring effects.

Findings

Proximity with Py enhances Gd magnetic order.

Spin-flop transition due to exchange-spring rotation.

Magnetoresistance sign change at the compensation temperature.

Abstract

Using a combination of magnetometry and magnetotransport techniques, we studied temperature and magnetic field behavior of magnetization in Py/Gd heterostructures. It was shown quantitatively that proximity with Py enhances magnetic order of Gd. Micromagnetic simulations demonstrate that a spin-flop transition observed in a Py/Gd bilayer is due to exchange-spring rotation of magnetization in the Gd layer. Transport measurements show that the magnetoresistance of a [Py(2 nm)/Gd(2 nm)]25 multilayer changes sign at the compensation temperature and below 20 K. The positive magnetoresistance above the compensation temperature can be attributed to an in-plane domain-wall, which appears because of the structural inhomogeneity of the film over its thickness. By measuring the angular dependence of resistance we are able to determine the angle between magnetizations in the multilayer and the magnetic field at different temperatures. The measurement reveals that due to a change of the chemical thickness profile, a non-collinear magnetization configuration is only stable in magnetic fields above 10 kOe.