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The electronic, magnetic, and thermal properties of polycrystalline Pr0.65Ca0.35-xSrxMnO3 (x=0–0.35) perovskites have been elaborately investigated. A huge enhancement of magnetoresistance (MR) (10% at H=100 Oe and 99% at H=0.5 T) has been observed in an x=0.1 sample around the metal-insulator (MI) transition temperature (TMI∼80 K) which is induced by the phase separation (PS). This study opens the possibility to search for the polycrystalline colossal magnetoresistive materials with a very high MR at low magnetic fields on the basis of PS phenomena for potential applications. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study that investigated the structure of 180° one-dimensional domain wall (DW) in a uniaxial ferromagnet in the presence of an external magnetic field arbitrarily oriented with respect to the DW. Influence of magnetic field on the structure of DW; Dependence of the effective widths of the distributions of both the polar and azimuthal angles of magnetization across the DW proper; Comparison if the dependence of the effective widths of the distribution of the polar angles.

Due to the Magnetohydrodynamic (MHD) effect, which degrades heat transfer coefficients by pulsation suppression of external magnetic field, on the electrically conducting flow, the wall with non-uniform electrical conductivity is employed in a free surface MHD-flow system for heat transfer enhancement. The non-uniform electrical conductivity distribution of the channel wall may create alternate Lorentz forces along spanwise direction, which can effectively produce flow disturbance, promote mixture, reduce the thickness of boundary layer, and enhance heat transfer. So the heat transfer performances enhanced by some conducting strips aligned with the mean flow direction on the insulating wall of free surface MHD-flow are simulated numerically in this paper. The flow behaviors, heat transfer coefficients, friction factors and pressure drops are presented under different Hartmann numbers. Results show that, in the range of Hartmann numbers 30≤Ha≤100, the wall with non-uniform conductivity can achieve heat transfer enhancements (Nu/Nu0) of about 1.2 to 1.6 relative to the insulating wall, with negligible friction augmentation. This research indicates that the modules with three or five conducting strips can obtain better enhancement effect in our research. Particularly, the heat transfer augmentation increases monotonically with increasing Hartmann numbers. Therefore, the enhancement purpose for high Hartman number MHD-flow is marked, which may remedy the depressing heat transfer coefficients by MHD effect. [ABSTRACT FROM AUTHOR]

The electronic, magnetic, and thermal properties of polycrystalline Pr0.65Ca0.35-xSrxMnO3 (x=0–0.35) perovskites have been elaborately investigated. A huge enhancement of magnetoresistance (MR) (10% at H=100 Oe and 99% at H=0.5 T) has been observed in an x=0.1 sample around the metal-insulator (MI) transition temperature (TMI∼80 K) which is induced by the phase separation (PS). This study opens the possibility to search for the polycrystalline colossal magnetoresistive materials with a very high MR at low magnetic fields on the basis of PS phenomena for potential applications. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]