The electronic structure of NdFe 10 M 2(M=Ti, V, Cr, Mn, Mo, W) compounds were obtained by the linear muffin tin orbit(LMTO) method, and the micro magnetic properties were examined through the total density of ...The electronic structure of NdFe 10 M 2(M=Ti, V, Cr, Mn, Mo, W) compounds were obtained by the linear muffin tin orbit(LMTO) method, and the micro magnetic properties were examined through the total density of state(TDOS) and the local density of state(DOS). The results suggest that there are two mechanisms which compete with each other and are responsible for variations in magnetic moments of NdFe 10 M 2 with intertitial N(or C) atoms, and the volume expansion leads to the enhancement of Fe Fe exchange interaction at 8i and 8f site, with the result that the magnetic moments at both sites increase. Meanwhile, the magnetic moments at 8j site decrease owing to the hybridization between 3d(Fe) and 2p(N or C) orbits.展开更多
Properties of GaAs single crystals grown at low temperatures by molecular beam epitaxy (LTMBE GaAs) have been studied. The results show that excessive arsenic atoms of about 1020 cm?3 exist in LTMBE GaAs in the form o...Properties of GaAs single crystals grown at low temperatures by molecular beam epitaxy (LTMBE GaAs) have been studied. The results show that excessive arsenic atoms of about 1020 cm?3 exist in LTMBE GaAs in the form of arsenic interstitial couples, and cause the dilation in lattice parameter of LTMBE GaAs. The arsenic interstitial couples will be decomposed, and the excessive arsenic atoms will precipitate during the annealing above 300°C. Arsenic precipitates accumulate in the junctions of epilayers with the increase in the temperature of annealing. The depletion regions caused by arsenic precipitates overlap each other in LTMBE GaAs, taking on the character of high resistivity, and the effects of backgating or sidegating are effectively restrained.展开更多
文摘The electronic structure of NdFe 10 M 2(M=Ti, V, Cr, Mn, Mo, W) compounds were obtained by the linear muffin tin orbit(LMTO) method, and the micro magnetic properties were examined through the total density of state(TDOS) and the local density of state(DOS). The results suggest that there are two mechanisms which compete with each other and are responsible for variations in magnetic moments of NdFe 10 M 2 with intertitial N(or C) atoms, and the volume expansion leads to the enhancement of Fe Fe exchange interaction at 8i and 8f site, with the result that the magnetic moments at both sites increase. Meanwhile, the magnetic moments at 8j site decrease owing to the hybridization between 3d(Fe) and 2p(N or C) orbits.
文摘Properties of GaAs single crystals grown at low temperatures by molecular beam epitaxy (LTMBE GaAs) have been studied. The results show that excessive arsenic atoms of about 1020 cm?3 exist in LTMBE GaAs in the form of arsenic interstitial couples, and cause the dilation in lattice parameter of LTMBE GaAs. The arsenic interstitial couples will be decomposed, and the excessive arsenic atoms will precipitate during the annealing above 300°C. Arsenic precipitates accumulate in the junctions of epilayers with the increase in the temperature of annealing. The depletion regions caused by arsenic precipitates overlap each other in LTMBE GaAs, taking on the character of high resistivity, and the effects of backgating or sidegating are effectively restrained.
