SmN; a zero-moment ferromagnetic semiconductor

The rare-earth nitrides condense into the NaCl structure with a slowly-varying lattice constant across the series. We have grown a number of them, as polycrystalline and/or epitaxial films, and so far find them all to be semiconductors with a ferromagnetic phase at low temperature. SmN is especially interesting for its near cancellation between spin and orbital moments, in which the spins order ferro-magnetically below 27 K with a net magnetic moment of order 0.03 $\mu _{B}$/Sm. It is thus a nearly fringe-field free ferromagnetic semiconductor that couples so weakly to an applied field that its coercive field is very large; both of these properties are attractive for spintronics.