Magnetism and magnetotransport in sputtered Co-doped FeSi films

FeSi is a non-magnetic narrow-gap semiconductor that can be doped n-type by Co, which also gives rise to magnetic order. Here we report on the growth of sputtered thin films of Fe0.8Co0.2Si, which are predominantly ε -phase (B20 lattice structure), and possess that phase's characteristic magnetotransport properties. The ordinary Hall coefficient shows that each Co atom donates roughly one electron, whilst the magnetometry suggests that each gives rise to close to one Bohr magneton of moment. These results indicate that a highly spin-polarised electron gas persists despite the inevitable disorder in these thin films, suitable for spintronic devices.