Exchange bias in epitaxial and polycrystalline thin film Ru2MnGe/Fe bilayers

Abstract

We report on thin film bilayers of the antiferromagnetic Heusler compound Ru₂MnGe and Fe, as well as the resulting exchange bias field at low temperatures and its temperature dependence. Epitaxial Ru₂MnGe/Fe bilayers show an exchange bias field up to 680 Oe at 3 K. For increasing temperatures, a linearly decreasing exchange bias field is found, which vanishes at 130 K. Furthermore, we grew polycrystalline Ru₂MnGe showing an exchange bias field up to 540 Oe, which vanishes around 30 K. By adding a very thin intermediate layer of Mn, the exchange bias field for polycrystalline samples has been increased by about 40%. We discuss differences between the epitaxial and polycrystalline films regarding magnetic and crystallographic properties and compare our results to already published work on this system.