Magnetotransport in phase-separated (Ga,Fe)N with gamma-Gay Fe4-yN nanocrystals

The magnetotransport in phase-separated (Ga,Fe)N containing γ′-GayFe4−yN(0<y<1) nanocrystals(NCs) is studied in the temperature range between 2 and 300 K. The evolution of the resistivity and ofthe magnetoresistance (MR) as a function of temperature points to two conduction mechanisms, namely, aconventional Arrhenius-type one down to 50 K and Mott variable range hopping at lower temperatures, wherethe spin-polarized current is transported between NCs in a regime in which phonon-scattering effects are notdominant. Below 25 K, the MR shows a hysteretic contribution at magnetic fields<1 T and proportional to thecoercive field. Anisotropic magnetoresistance with values one order of magnitude greater than those previouslyreported forγ′-Fe4N thin films over the whole considered temperature range confirms that the observed MR inthese layers is determined by the embedded nanocrystals.