The magnetic and magnetotransport properties of several series of sandwiches consisting of two ferromagnetic layers (Ni, Co, Ni80Fe20) separated by a noble metal (Cu, Ag, Au) are described. In order to vary the relative orientation of the magnetizations of the two ferromagnets, one of them was constrained by exchange anisotropy (e.g., NiFe/Fe50Mn50). The ferromagnetic layers are magnetically soft and not coupled antiparallel, giving very large changes of resistance at low fields. At room temperature relative changes ΔR/R of 4.1% in 10 Oe for Si/Ta 50 Å/NiFe 62 Å/Cu 22 Å/NiFe 40 Å/FeMn 70 Å/Ta 50 Å and 8.7% in 20 Oe has been obtained for a structure based on Co/Cu/Co layers. The magnetoresistance versus the thickness of the ferromagnetic layer shows a broad peak near 80 Å for Ni, Co and NiFe, demonstrating the importance of bulk rather than interfacial spin-dependent scattering, in contrast to Fe/Cr multilayers. The magnetoresistance decreases exponentially with increasing interlayer (Cu and Au) thickness, indicating that the magnetoresistance is due to the exchange of polarized electrons from one ferromagnetic layer to the other. The variation with Ag interlayer thickness is different for structural reasons.

This paper proposes a mechanism for topographical features formed during pulsed laser texturing of Ni-P magnetic disk substrates. A salient feature of the process is the ability to raise a central peak in the irradiated spot, providing a low contact area bearing for the slider-head of a computer hard drive. Formation of topography is believed to involve gradient capillary forces acting at the surface of the molten pool (Marangoni effect). However, the central peak cannot be explained with thermo-capillary forces alone. Therefore, it is suggested that a compositional gradient due to the depletion of a surfactant at the molten surface provides the necessary condition to reverse the capillary force in the central region. This perspective is investigated using finite element modeling of the Lagrangian fluid mechanics coupled with heat and mass diffusion.

We present comprehensive results on the magnetoresistive properties of spin-valve sandwiches comprising glass/M(1)/Cu/NisoFe2o/Fe5OMn»/Cu, where M(1) is a ferromagnetic transition metal or alloy (Co, Ni, Ni80Fe20). We discuss the thermal variation of the magnetoresistance (AR/R) and its dependence on the thicknesses of the layers constituting the active part of the spin-value sandwich [i.e., M( 1)/Cu/N(Fe]. An almost linear decrease of b,R/R is observed between 77 and 320 K. For a given ferromagnetic material, bR /R extrapolates to zero at a temperature T"sy significantly lower than the Curie temperature, and independent of the ferromagnetic layer thickness. We have identified spin-$ and spin-$ intermixing by spin-wave scattering as responsible for the thermal decrease of the magnetoresistance. We show that the magnetoresistance arises within the "active" parts of the ferromagnetic layers of 0 thickness of about 90 A located next to the M/Cu interfaces. We give a phenomenological expression relating AR /R to the longer of the two spin-dependent mean free paths, and to current shunting in the inactive part of the sandwich. The thickness of the active region is independent of temperature.

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