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Transport and magnetic properties of amorphous Fe-Dy-Oxide thin films

Novel amorphous FeDy-Oxide thin films, deposited by e-beam evaporation, show room-temperature magnetism, as well as high electrical conductivity, carrier mobility, and optical transparency that is very promising for a multitude of applications. We have systematically studied transport, optical and magnetic properties of a large set of films deposited on Quartz and SiO2/Si substrates at different oxygen partial pressures [10-6,10-8,10-9 Torr]. Atomic ratios of Fe to Dy in the films (confirmed by EDS) varied from 0.3 to 6, but all samples had resistivity less than 2.5E-03 Ohm*cm. Optical bandgap of as prepared films was 2.4±0.1 eV. The films showed high ordinary Hall mobility (~10 cm2/V-s) which is among the highest for amorphous oxides, as well as anomalous Hall mobility (~102 cm2/V-s). At low temperatures there was two step magnetization that suggests coexistence of two magnetic phases below H=0.08 T and ferromagnetic phase at higher fields. Select films were taken through cyclic annealing (300-700K) which after 3 cycles resulted in still amorphous, thermally stable homogeneous FeDyO material. These results will motivate further investigation into the fundamental mechanisms responsible for these properties and how they might be tuned for integration in devices.