Magnetic and magneto-transport properties of Mn4N thin films by Ni substitution and their possibility of magnetic compensation
Résumé
Ferrimagnets are of interest in spintronics owing to the enhancement of spin transfer and spin–orbit torque in the vicinity of the magnetic compensation point. Here, we study the possibility of achieving compensation at room temperature in Mn4−xNixN films grown on SrTiO3(001) substrates by molecular beam epitaxy. The magnetic and magneto-transport properties of 30-nm-thick epitaxial Mn4−xNixN films (x = 0, 0.1, 0.25, and 0.5) were investigated. Ni introduction in Mn4N causes the spontaneous magnetization (MS) to decrease by 45% at x = 0.1 and by 75% at x = 0.25. All samples exhibited the perpendicular magnetic anisotropy required for spintronic applications as well as displaying a sharp magnetization reversal. Remarkably, the sign of the anomalous Hall resistivity changed in the samples between x = 0.1 and 0.25. Further, the magnetization increased for x = 0 and 0.1 and decreased for x = 0.25 when the temperature was decreased. Based on these results, we propose that there is a magnetic compensation composition between x = 0.1 and 0.25, where the magnetization of Mn4−xNixN becomes zero at room temperature. The small MS and perpendicular magnetic anisotropy of the Mn4−xNixN thin films, thus, make them suitable candidates for use in spin transfer torque-based devices.
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