We report the crystal structures and magnetic properties of [Pt/Co]3/Pt/r-oriented Cr2O3 multilayers fabricated by DC-RF magnetron sputtering method. From the results of 2θ-θ x-ray diffraction profile, highly r-plane (1102) oriented Cr2O3 film grows. Preferable orientation of Pt and Co films is (111). The lattice spacing of r-plane Cr2O3 was 0.363 nm. This value is in agreement with that of the bulk, indicating that the film is grown without stress from the substrate. From the reciprocal space mapping, both the substrate and film peaks were visible for (22010) plane, while no peaks were observed for the (2208) plane. The magnetic property of the multilayer is investigated by magnetic field (H) dependences of the magnetizations (M). The exchange bias filed, HEB, was -150Oe at 5K, which is the first observation using highly ordered r-plane Cr2O3 film.
The Cr2O3 thin films are fabricated on YAlO3(YAO)(0 0 1) substrates etched with 5M and 12M NaOH solutions. After the etching with 12M NaOH solution, the YAO surface showed step-terraces structure with the step height of one unit. The surface morphology of Cr2O3 thin films grown on 5M, 12M etched YAO and r-cut sapphire substrate is almost similar even though the crystal structure of YAO is orthorhombic. Focusing on one grain of Cr2O3 thin film, the surface is two dimensionally flat with approximately unit step of 0.36nm. The Cr2O3 films expitaxially grow with the relationship of Cr2O3±[1 1 0] // YAO[1 0 0], Cr2O3±[1 1 1] // YAO[0 1 0], double-sign corresponds, and Cr2O3(1 1 0 2) // YAO(0 0 1).
AlCu binary alloys were irradiated with 16 MeV Au, 4.5 MeV Ni or 4.5 MeV Al ions at room temperature. Changes in surface hardness and the local atomic structure around Cu atoms were examined by using the Vickers hardness measurement and the EXAFS measurements, respectively. Some specimens were aged at 453K and Vickers hardness was measured. The computer simulation was also performed by using the rate equation method. The hardness of irradiated specimens increased much faster than that of the aged specimens and it became larger than the maximum value of the hardness for the aged specimens. The comparison of the experimental EXAFS result with that of FEFF simulation suggests that the ion irradiation produced small Cu precipitates in the specimens. The computer simulation visualized the growth process of Cu precipitates during the irradiation, and the result qualitatively corresponds to the experimental result.