RECENT RESULTS ON THE GIANT MAGNETORESISTANCE IN MAGNETIC MULTILAYERS(ANISOTROPY, THERMAL VARIATION AND CCP-GMR)

We present some recent results obtained on the electrical transport pr operties in magnetic multilayers. Three points are addressed, The firs t one is an experimental demonstration of the existence of an intrinsi c anisotropy of the giant magnetoresistance (GMR), The experiments hav e been carried out on spin-valve samples for which there is no contrib ution of the usual anisotropic magnetoresistance to the observed magne toresistance. The GMR amplitude is found to be larger (lower) in the d irection perpendicular (parallel) to the sensing current. The second p oint concerns a quantitative analysis of the thermal variation of the CIP (current-in-plane) GMR in magnetic multilayers, This analysis is b ased on a semi-classical theory including the spin-intermixing due to spin-flip scattering by magnons. This approach allows quantitatively e valuation of the respective weights of the various contributions to th e thermal decrease in GMR: (i) scattering by magnons in the bulk of th e ferromagnetic layers; (ii) phonon scattering in the non-magnetic spa cer layer, and (iii) interfacial scattering by paramagnetic interfacia l layers which may form as the temperature is increased. The third poi nt is a theoretical investigation of the CPP (current perpendicular to the plane) electrical transport through an interface between two semi -infinite metallic materials, it is shown that when a potential step U exists at such an interfacial, this step gives rise to an interfacial resistance proportional to U-2. It also leads to the existence of lar ge oscillations in the electric fields on both sides of the interface.