PUB - Publikationen an der Universität Bielefeld

The exchange bias effect is commonly used to shift the coercive field of a ferromagnet. This technique is crucial for the use of magnetic tunnel junctions as logic or memory devices. Therefore, an independent switching of the two ferromagnetic electrodes is necessary to guarantee a reliable readout. Here, we demonstrate that the intrinsic exchange bias effect of Ni-Mn-Sn can be used to apply a unidirectional anisotropy to magnetic tunnel junctions. For this, we use epitaxial Ni-Mn-Sn films as pinning layers for microfabricated CoFeB/MgO/CoFeB magnetic tunnel junctions. We compare the exchange bias field (H-EB) measured after field cooling in -10 kOe external field by magnetization measurements with H-EB obtained from tunnel magnetoresistance measurements. Consistent for both methods, we find an exchange bias of about H-EB = 130 Oe at 10 K, which decreases with increasing temperature and vanishes above 70 K. (C) 2015 AIP Publishing LLC.