Magnetotransport in phase-separated (Ga,Fe)N with $\gamma$'-Ga$_y$Fe$_{4-y}$N nanocrystals

TL;DR

This study investigates the magnetotransport properties of phase-separated (Ga,Fe)N with embedded $\gamma$'-Ga$_y$Fe$_{4-y}$N nanocrystals, revealing temperature-dependent conduction mechanisms and significant anisotropic magnetoresistance influenced by the nanocrystals.

Contribution

It provides new insights into the conduction mechanisms and magnetoresistance behavior in (Ga,Fe)N with nanocrystals, highlighting the role of nanocrystals in magnetic transport properties.

Findings

Resistivity follows Arrhenius and Mott variable range hopping mechanisms.

Hysteretic magnetoresistance appears below 25 K and fields <$1 T.

Anisotropic magnetoresistance exceeds previous reports for $\gamma$'-Fe$_4$N$ thin films.

Abstract

The magnetotransport in phase-separated (Ga,Fe)N containing $\gamma$'-Ga$_y$Fe$_{4-y}$N (0\,$<$\,y\,$<$1) nanocrystals (NCs) is studied in the temperature range between 2\,K and 300\,K. The evolution of the resistivity and of the magnetoresistance (MR) as a function of temperature points at two conduction mechanisms: namely a conventional Arrhenius-type one down to 50\,K, and Mott variable range hopping at lower temperatures, where the spin-polarized current is transported between NCs in a regime in which phonon-scattering effects are not dominant. Below 25\,K, the MR shows a hysteretic contribution at magnetic fields $<$1\,T and proportional to the coercive field. Anisotropic magnetoresistance with values one order of magnitude greater than those previously reported for $\gamma$'-Fe$_4$N thin films over the whole considered temperature range, confirms that the observed MR in these layers is determined by the embedded nanocrystals.