Exchange bias of mu-metal thin films

TL;DR

This study investigates the exchange bias properties of mu-metal thin films with FeMn, revealing how buffer layer material and ferromagnet thickness influence magnetic behavior, with implications for sensor applications.

Contribution

It is the first detailed analysis of exchange bias in mu-metal thin films, highlighting the effects of buffer layer orientation and material on magnetic properties.

Findings

Exchange bias and coercivity scale inversely with ferromagnet thickness.

(111) Cu buffer layers maximize exchange bias effects.

Amorphous Ta buffers help preserve mu-metal's soft magnetic properties.

Abstract

The exchange bias of the soft ferromagnet mu-metal, Ni77Fe14Cu5Mo4, with the metallic antiferromagnet Fe50Mn50 has been studied as a function of ferromagnet thickness and buffer layer material. Mu-metal exhibits classic exchange bias behavior: the exchange bias (HEB) and coercive fields scale inversely with the ferromagnet's thickness, with HEB varying as the cosine of the in-plane applied field angle. While the exchange bias, coercivity, and exchange energy are greatest when the buffer layer material is (111) oriented Cu, amorphous Ta buffers allow the mu-metal to retain more of its soft magnetic character. The ability to preserve soft ferromagnetic behavior in an exchange biased heterostructure may be useful for low field sensing and other device applications.