Structures, transport, magnetic properties, and first principle calculation results will be reported for the two dimensional layered structured perovskite compounds Sr2-xNdxCoO4 (x = 0.5, 0.75, 1, 1.25). Structure refinement results revealed that these compounds crystallized in K2NiF4-type structures with space group I4/mmm. The temperature dependence of resistivity showed semiconductor like behavior for these samples. It was found that the lattice parameter c decreases as the doping level x increases. The compounds exhibited a paramagnetic to ferromagnetic transition at temperatures of about 170, 125 K for the x = 1 and 0.75 samples, respectively. The temperature dependence of resistivity for the samples can be well fitted by the 2D variable hoping (VRH) model ρ = ρo exp(T0/T)1/3 (where ρo is a material specific characteristic conductance, with unit Ω−1, T0 is a material specific characteristic temperature in K) over the whole measured temperature range. First principles calculations indicated that the Nd doped Sr2CoO4 compounds show high spin polarization.

Abstract-Recently, room-temperature ferromagnetism was reported in Cu-doped AlN film. However, a systematic study on the magnetic mediation of intrinsic vacancy is still absent and the origin of ferromagnetism of Cu-doped AlN remains unclear. We investigate the magnetic properties of Cu-doped AlN by firstprinciples calculations. Our results reveal that the ferromagnetism is very weak for Cu substitution only. However, both the anion and cation vacancies can mediate the ferromagnetism effectively. Under the N-poor conditions, the defect complex with N vacancy has much lower formation energy and the origin of ferromagnetism can be attributed to the Nvacancy mediated p-d hybridization.