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排序方式: 共有128条查询结果,搜索用时 93 毫秒
1.
Yi Kai Zhou Sung Woo Choi Shigeya Kimura Shuichi Emura Shigehiko Hasegawa Hajime Asahi 《Journal of Superconductivity and Novel Magnetism》2007,20(6):429-432
GaGdN layers were grown at temperatures below 300°C by radio-frequency plasma-assisted molecular beam epitaxy on sapphire
substrates. GaGdN samples with high Gd concentration as high as 12.5% were obtained by lowering the growth temperature. X-ray
diffraction results showed no obvious secondary phase, which means that the phase separation can be suppressed by the growth
at low temperatures. All samples, including those grown at room temperature, showed ferromagnetic characteristics. Photoluminescence
emission was observed, though spectra exhibit broad and sharp luminescence bands related to many kinds of defects. It is suggested
that electrons coming from defects, especially, nitrogen vacancy, stabilize ferromagnetism, and that the carrier-induced ferromagnetism
occurs in the low-temperature-growth GaGdN. 相似文献
2.
Segregation in sputtered Co-Cr films 总被引:1,自引:0,他引:1
The segregation growth process in sputtered Co-Cr films is investigated by examining the effect of substrate temperature on the segregated microstructure and magnetic properties. In sputtered Co-25at%Cr films, segregation occurs below 560°C, and both the saturation magnetization and the perpendicular anisotropy constant show a maximum around a substrate temperature of 300°C, where a specific microstructure, called a CP (chrysanthemum-like pattern) structure, is observed. The results suggest that the CP structure becomes observable in the highly segregated state and generates high perpendicular anisotropy. A new segregation growth model is derived from the results of the CP structure observations. Using this model, it is possible to explain the continuous transition of the magnetization mode between the continuous and the particulate modes. 相似文献
3.
K. ôno S. Kobayasi M. Shinohara K. Asahi H. Ishimoto N. Nishida M. Imaizumi A. Nakaizumi J. Ray Y. Iseki S. Takayanagi K. Terui T. Sugawara 《Journal of Low Temperature Physics》1980,38(5-6):737-745
Two-stage nuclear demagnetization has been performed using PrCu6 and Cu as coolants. The Cu nuclear stage reached temperatures as low as 10 K with a rate of temperature rise of less than a few K/h. The corresponding conduction electron temperature is estimated to be less than 50 K. A nuclear orientation thermometer of Al
54Mn has been successfully used to measure temperatures down to 10 K.Supported by the Japan Society for the Promotion of Science. 相似文献
4.
5.
6.
Annealing Effect in GaDyN on Optical and Magnetic Properties 总被引:1,自引:0,他引:1
Yi-Kai Zhou Masahiro Takahashi Shuichi Emura Shigehiko Hasegawa Hajime Asahi 《Journal of Superconductivity and Novel Magnetism》2010,23(1):103-105
The annealing effect on the optical and magnetic properties of the GaDyN layers was studied. The PL intensities of yellow
and green bands as well as the intra-4f orbital transition of Dy3+ ions were found to decrease for the samples annealed at 900 and 1000 °C. It is supposed that the intra-4f orbital transition is related to the broad peak luminescence coming from defects. Increasing the annealing temperature, the
magnetization becomes smaller. It is considerable that the number of electrons coming from defects was reduced by the annealing
treatments and that the ferromagnetism in GaDyN is attributed as carrier induced ferromagnetism. 相似文献
7.
Room-temperature excitonic resonances in the optical absorption spectrum of InGaP/lnGaAlP multiquantum wells (MQWs) are observed for the first time. Well resolved heavyhole and light-hole excitons are observed at 100K. From the step-like structure of the absorption spectrum, the conduction-band discontinuity ?Ec is estimated to be 0.46 of the bandgap difference ?Eg. 相似文献
8.
9.
A. V. Andrianov K. Yamada H. Tampo H. Asahi V. Yu. Nekrasov Z. N. Petrovskaya O. M. Sreseli N. N. Zinov’ev 《Semiconductors》2002,36(8):878-882
The low-temperature time-resolved photoluminescence of polycrystalline GaN layers grown by molecular beam epitaxy on metal substrates (Mo and Ta) was investigated. The photoluminescence spectra observed include two emission bands in the ultraviolet spectral region. We assign one of these bands to recombination processes inside cubic nanocrystallites, which are formed in the hexagonal polycrystalline GaN host. The recombination radiation of cubic nanocrystallites is enhanced due to predominant trapping of the nonequilibrium electron-hole pairs in these crystallites. 相似文献
10.
Wakita K. Kawamura Y. Yoshikuni Y. Asahi H. Uehara S. 《Quantum Electronics, IEEE Journal of》1986,22(9):1831-1836
The first measurements to be made of large anistropic electroabsorption and modulation of long-wavelength light propagating along the plane of InGaAs/InAlAs multiple quantum well (MQW) structures grown by molecular beam epitaxy (MBE) are reported. Photocurrent response of waveguide p-i-n diodes is studied for incident light polarization parallel and perpendicular to the MQW layers. Photocurrent increase with reverse bias throughout the entire photoresponse spectrum is observed for both polarizations. The MQW p-in optical modulator shows a capacitance-limited pulse response of 250 ps and the modulation depth is 14 percent. 相似文献