Nature © Macmillan Publishers Ltd 19988 localizing effect will lead to saturation of the magnetoresistance. Yet all the data except for the perovskite manganites and the strongly localized Eu 0.99 Gd 0.01 Se (n ¼ 0:0002 per unit cell) are on samples that satisfy k F l Ͼ 1, indicating the weakly localizing nature of pure spin scattering, as expected.At low carrier densities, one should be wary of magnetizationdependent bandshift, because the exchange energy might be comparable to the Fermi energy. When the carriers are introduced by doping, this is not important, but for semimetals (Tl 2 Mn 2 O 7 may be an example 19,20 ) and mixed valent compounds 21 the carrier density itself might become field-and temperature-dependent.We conclude that on elementary theoretical grounds and with some support from the limited data available, the very simplest Born approximation gives a good account of the trends in bulk magnetoresistance over two decades in density, in materials and in models of magnetism that have otherwise very little in common. The most evident deviation from a simple scaling law is in the perovskite manganites, for which there is overwhelming evidence that their 'colossal' magnetoresistance arises from the localization of carriers by lattice distortions that are themselves coupled to the magnetic degrees of freedom.This organizing principle suggests that insulating ferromagnets, lightly doped into the metallic regime, are a promising class of materials in which to search for large bulk magnetoresistance. As a final cautionary note, we also point out that the scaling shown in equation (4) and in Fig. 1 nevertheless implies rather small values of the absolute bulk magnetoresistance at the millitesla fields of technological interest. Ⅺ

No abstract

Impact of ultrathin transition metal buffer layers on Fe 3 O 4 thin films J. Appl. Phys. 107, 09B101 (2010); 10.1063/1.3350910 CPP transport properties of polycrystalline Fe 3 O 4 thin films sputtered on Cu underlayers J. Appl. Phys. 97, 10C315 (2005); 10.1063/1.1847191Fabrication and magnetoresistive effect of current perpendicular to plane devices using half-metallic Fe 3 O 4 thin films on metallic films

Amorphous silicon (a-Si) was crystallized by metal-induced crystallization (MIC) using a Ni standard absorption solution. The a-Si films spin-coated with a 5000 ppm Ni solution were crystallized at as low as 500 °C. Needlelike morphology, developed as a result of the migration of NiSi2 precipitates, appears in the MIC poly-Si. The growth of the needlelike crystallites proceeds to a direction parallel to 〈111〉. The a-Si can be fully crystallized at 500 °C for 20 h.

A new fabrication process for polycrystalline silicon (poly-Si) thin-film transistors (TFTs) on glass substrate is reported. Amorphous silicon (a-Si) was crystallized by metal-induced crystallization (MIC) using a Ni solution for low-temperature crystallization. The a-Si film spin-coated with a 5000 ppm Ni solution was fully crystallized at 500°C. The poly-Si TFT made of the poly-Si exhibited a field-effect mobility of 105 cm2/Vs and a threshold voltage of -4 V. The high performance of the poly-Si TFT appears to be due to the absence of intragrain microdefects in the poly-Si, which is confirmed from the plane-view TEM image.