Direct observation of the magnetic proximity effect in amorphous exchange-spring magnets by neutron reflectometry

TL;DR

This study uses neutron reflectometry to directly observe the magnetic proximity effect in an amorphous exchange-spring magnet, revealing how magnetic properties extend across layers near their transition temperatures.

Contribution

It provides the first direct measurement of the magnetic proximity effect in amorphous exchange-spring magnets using neutron reflectometry.

Findings

Proximity effect observed 7 K above the embedded layer’s T_c

Magnetization profile extends over 50 Å

Demonstrates control of magnetic states in layered amorphous structures

Abstract

In this letter we report a direct observation of a magnetic proximity effect in an amorphous thin film exchange-spring magnet by the use of neutron reflectometry. The exchange-spring magnet is a trilayer consisting of two ferromagnetic layers with high $T_c$'s separated by a ferromagnetic layer, which is engineered to have a significantly lower $T_c$ than the embedding layers. This enables us to measure magnetization depth profiles at which the low $T_c$ material is in a ferromagnetic or paramagnetic state, while the embedding layers are ferromagnetic. A clear proximity effect is observed 7 K above the $T_c$ of the embedded layer, with a range extending 50 $\unicode{xC5}$.