Abstract
Polycrystalline ferromagnetic GdNx films were fabricated at different N-2 flow rates (f(N2)) to modify N-vacancy concentration so as to study its influence on electrotransport. Metal-semiconductor transition appears at Curie temperature (T-C) of similar to 40K. Temperature-dependent magnetoresistance (MR) shows a peak at T-C. The films at f(N2) = 5, 10, 15, and 20 sccm show MR of -38%, -42%, -46%, and -86% at 5K and 50 kOe, respectively. Above 15 K, MR is from colossal MR and from both colossal and tunneling MR below 15K. The enhanced MR at f(N2) = 20 sccm is attributed to large spin polarization of half-metallicity in GdNx with low N vacancies. (C) 2013 AIP Publishing LLC.