Exchange bias of mu-metal thin films

The exchange bias of the soft ferromagnet mu-metal, Ni77Fe14Cu5Mo4Ni77Fe14Cu5Mo4, with the metallic antiferromagnet Fe50Mn50Fe50Mn50 has been studied as a function of ferromagnet thickness and buffer layer material. Mu-metal exhibits classic exchange bias behavior: the exchange bias (HEB)(HEB) and coercive fields scale inversely with the ferromagnet's thickness, with HEB varying as the cosine of the in-plane applied field angle. Ta buffers, rather than Cu, allow the mu-metal to retain more of its soft magnetic character while exhibiting exchange bias. The ability to preserve soft ferromagnetic behavior in an exchange biased heterostructure may be useful for low field sensing and other device applications.

► Mu-metal/FeMn bilayers exhibit classic exchange bias behavior.
► Mu-metal's soft magnetic properties are retained most effectively with Ta buffers.
► Differences in interfacial exchange energy are structural in origin.