The influence of nitrogen vacancies on the magnetic behaviour of rare-earth nitrides

The rare-earth nitrides are ferromagnetic semiconductors with promise for spintronic devices. Their most common dopants are nitrogen vacancies (V_N), with a small enough energy of formation that they exist at of order 1% in epitaxial films. Here we report preliminary investigations of their effect on the magnetic states of two of them in the series, GdN and EuN. In the former we find an enhanced Curie temperature at very high V_N concentration, and the Eu²⁺ ions associated with V_N in the latter show strong exchange with their Eu³⁺ neighbours that might form the basis of a diluted magnetic semiconductor.