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When plotting the anomalous Hall coefficient ( R s ) and longitudinal resistivty ( ρ xx ) for a series of annealed Ga 1− x Mn x As epilayers ( x ≈0.055), we find the value of the scaling parameter n , from R S = cρ xx n , to range from one, as-grown, to two at an optimal annealing temperature to values greater than three for higher annealing temperatures, similar behavior to certain inhomogeneous systems. This scaling relationship can be a new method to detect secondary phases in ferromagnetic semiconductor systems.

Dielectric SrMoO4 thin films were deposited from Sr2FeMoO6 target in oxygen atmosphere, showing obvious M–H hysteresis loops at room temperature. It was revealed by transmission electron microscopy that SrFeO3 nanoparticles are dispersed in the SrMoO4 grains, to which the hystersis loops of the thin films are ascribed. This SrMoO4 thin film can be useful as a barrier material for Sr2FeMoO6-based devices, owing to easy fabrication process and compatibility with Sr2FeMoO6. Magnetic SrFeO3 nanoparticles are expected to enhance tunneling magnetoresistance.

Epitaxial growth of the ferromagnetic semiconductors GaMnP:C and GaMnN has been investigated by Gas Source Molecular Beam Epitaxy (GSMBE). GaMnP:C films grown with 9.4% Mn are found to be p-type with hysteretic behavior to room temperature. GaMnN films grown at 700 °C with 2.8% Mn show hysteresis at 300 K, while temperature-dependent magnetization measurements indicate that the magnetism may persist to much higher temperatures (> 325 K). Samples of AlGaMnN have also been prepared for the first time that show improved surface morphology compared to GaMnN but which show only paramagnetic behavior.

Epitaxial NiO films (epi-NiO) were successfully doped with Al by performing sequential deposition of NiO and AlO x by pulsed laser deposition. Surface morphology and crystallinity were confirmed by atomic force microscope images and X-ray diffraction, indicating that the samples were grown epitaxially. Resistance switching (RS) phenomena of Al-doped NiO films were investigated using epitaxial SrRuO3 (SRO) and CaRuO3 (CRO) as the bottom (BE) and top electrode (TE), respectively. When the epi-NiO/SRO interface was modified by inserting either a 1-nm-thick epitaxial AlO x layer or a 5-nm-thick epitaxial 10% Al-doped NiO (Al0.1Ni0.9O x ) layer, the RS of epi-NiO remained unchanged. However, when the CRO/epi-NiO interface was modified by inserting a 1-nm-thick epitaxial AlO x layer or a 5-nm-thick Al0.1Ni0.9O x layer, switching behavior was significantly changed; in the case of the 1-nm-thick epitaxial AlO x layer, the switching behavior completely disappeared, while in the case of 5-nm-thick Al0.1Ni0.9O x layer, number of cells which exhibited RS was drastically decreased. The switching phenomena may be suppressed due to the presence of Al cations whose free energy for oxidation is much lower than that of Ni. Our experimental results suggest that oxygen ions migration at the TE/epi-NiO interface may play a critical role in bipolar RS of epi-NiO. The relation between RS and free energy for oxidation is discussed.