Conductivity of high-mobility epitaxial GdN

Abstract

We report electron transport studies of a (001) GdN film grown on the square net presented by the (001) surface of LaAlO3, motivated by recent advances in epitaxial thin-film growth of several lanthanide nitrides. The film we have grown for the purpose is characterised by in-situ RHEED and ex-situ XRD and XRR to show the best crystallinity and smoothest surfaces we have accomplished to date. It shows a clear ferromagnetic transition at $\sim 70$ K with a saturation magnetisation within uncertainly of 7 $\mu$B/Gd${}^{3+}$ ion, a remanence of 5 $\mu$B/Gd${}^{3+}$ ion and a coercive field of $\sim$5 mT. It is doped by $\sim 1$% nitrogen vacancies that introduce $\sim 3\times 10^{20}$ cm${}^{-3}$ electrons into the conduction band. The resistivity shows transport in a conduction band doped to degeneracy by $\sim 0.01$ electrons/formula unit with a residual resistance ratio of 2 and a Hall resistivity permitting easily-separated ordinary and anomalous Hall components. The mobility is an order of magnitude larger than we have found in earlier films.

arXiv comment6 pages, 6 figures