Solid-phase epitaxy of Co2Fe0.4Mn0.6Si full-Heusler alloy electrodes in (001)-textured MgO-based magnetic tunnel junctions
Kenta Watanabe, Mikihiko Oogane, Takafumi NakanoWe demonstrated solid-phase epitaxy of Co2Fe0.4Mn0.6Si (CFMS) full-Heusler alloy electrodes in (001)-textured MgO-based magnetic tunnel junctions (MTJs) fabricated on thermally oxidized Si substrates. Initially amorphous CFMS electrodes crystallized into a (001)-textured structure templated by the adjacent MgO barrier during ex situ annealing without the use of any crystalline seed layers. The corresponding single CFMS thin films exhibited the (002) superlattice reflection, indicating B2 ordering. The CFMS/MgO-based MTJs exhibited high tunnel magnetoresistance ratios of 154% at room temperature and 347% at 40 K. These results highlight solid-phase epitaxy as a simple and effective route for integrating Heusler alloy-based MTJs into practical spintronic devices.