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The annealing effect on the magnetic phase diagram of the Y-Fe amorphous alloy system has been investigated by means of differential magnetic susceptibility. Y-Fe amorphous alloys annealed at 250 degrees C for 30 min exhibit a re-entrant spin-glass behaviour in a similar manner to the as-prepared samples in an applied magnetic field. The Curie temperature is enhanced but the spin-freezing temperature Tf is depressed by annealing. These facts suggest that the Fe-Fe interatomic distance, which significantly influences the magnetic properties, increases on annealing. The magnetic phase diagram of the Y-Fe amorphous alloy system in an applied magnetic field is similar to that of various re-entrant spin-glass-type Fe-based amorphous alloy systems in zero magnetic field.

Experimental researches of quantum transport properties of semiconductor two-dimensional electron systems in Si-MOSFETs and GaAs/AlGaAs heterostructures in high magnetic fields up to 27 T and at low temperatures down to 20 mK are performed. Analysis of the Hall conductivity of Si-MOSFETs based on a mobility edge model shows that the temperature dependence of the mobility edge can not be explained by existing theory of localization. The fractional quantum Hall effect is observed at the filling factor of 1/7 in heterostructures. Sample size dependence and magnetic field dependence of the breakdown of the integral quantum Hall effect in heterostructures reveal that the Hall current is carried not by the edge states but by the extended states in the localization in the bulk of the two-dimensional systems.

The electrical resistivity under magnetic fields has been investigated for Pb2Sr2Y1-xCaxCu3O8, single-crystal Bi2Sr2CaCu2O8 and low-T(c) (La.Eu) 2-x (Ba,Sr)XCuO4. The upper critical field and the resistive tall In the lower portion of the superconducting transition curve are discussed.

Quantum transport experiments of Si-MOS inversion layers have been done at temperatures between 50 mK and 1.45 K and in magnetic fields between 14 and 23 T using samples having two grades of electron mobility. The Hall conductivity were analyzed employing a model calculation to derive the temperature dependence and the magnetic field dependence of the mobility edge. At low temperatures, the mobility edge was independent of temperature and independent of magnetic field suggesting the mobility edge is dominated by a macroscopic potential fluctuations. The temperature dependence of the mobility edge at high temperatures can not be explained by the existing theory of localization in Landau subbands in two dimensional systems and that of the temperature dependence of the inelastic scattering in the zero magnetic field.

The Cu-63/Cu-65-NMR study has been performed on the copper oxide superconductors La2-xBaxCuO4 (x = 0.11 approximately 0.14). Neither the internal magnetic field larger than 1KOe nor the distribution in the electric field gradient at the Cu site has been observed at 4.2K. The structural phase transition temperature T(d2) of the sample x = 0.13 was found to be higher than 60K.