NdN: An intrinsic ferromagnetic semiconductor

The rare-earth nitrides have recently regained attention due to findings that most members of the series are intrinsic ferromagnetic semiconductors, a class of materials that is crucial for the development of spintronics devices. Here we present a study of NdN thin films, with films grown via molecular beam epitaxy. Optical transmission measurements revealed a band gap of about 0.9 eV, while resistivity measurements confirmed semiconducting behavior with a negative temperature coefficient of resistance, though semimetallic behavior could not be ruled out. The room temperature resistivity of 0.6m[Omega] cm indicates strong doping by nitrogen vacancies. Magnetization measurements show a ferromagnetic moment of 1.0 + or - 0.2 mu sub()Bbelow the Curie temperature T sub()Cof 43 + or - 1 K, strongly suppressed from the Hund's rules value of 3.27 mu sub()Bper ion. The ferromagnetic moment is strongly quenched and the T sub()Cis enhanced compared to previously studied bulk NdN, and crystal field calculations reveal that the quenched moment is likely due to lattice strain. X-ray magnetic circular dichroism measurements show that the magnetic moment is orbital dominant, placing NdN in the same category as SmN, an intrinsic ferromagnetic semiconductor with an orbital-dominant ferromagnetic moment.