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The magnetic and magnetocaloric properties of the LuFe2–xMnxO4 + δ(x= 0, 0.05, 0.12) system have been studied. A partial substitution of manganese for iron leads to a noticeable decrease in the magnetization and the magnetocaloric effect. It has been shown that the magnetocaloric effect in LuFe2–xMnxO4 + δsamples is determined by several mechanisms.

Abstract: The transverse magnetoresistance and the Hall effect of Fe100 −x Al x ordered alloys with x = 26.5−34.1 at. % are studied at temperatures of 77 and 295 K. No saturation is found in the field dependences up to 17 kOe. The magnetoresistance is negative, depends nonmonotonically on the Al concentration, and reaches a maximum |ΔR/R| = 1.6% in the concentration range from 28 to 30 at. %. The coefficient of the anomalous Hall effect depends nonlinearly on the Al concentration and resistivity: it increases to a lesser extent as compared to the resistivity at x = 26–30 at. % and decreases with increasing resistivity at x > 30 at. %. An explanation is proposed for the observed anomalies in the magnetotransport properties in the framework of the model developed for the inhomogeneous magnetic microstructure of the Fe100 −x Al x ordered alloys.

Abstract: The possibility of creating room-temperature intrinsic ferromagnetism in a highly doped oxide semiconductor has been investigated. The results indicate that such state of a ferromagnetic semiconductor can be achieved by magnetron sputtering deposition of a semiconductor oxide doped with a transition metal followed by low-temperature vacuum annealing.