COMPARISON OF SEMICLASSICAL AND REAL-SPACE QUANTUM THEORIES OF GIANT MAGNETORESISTANCE

We carried out a quantitative comparison of two existing theories (semi-classical: Camley and Barnas, versus real-space quantum: Vedyaev, Dieny, Ryzhanova) of giant magnetoresistance in spin-valve multilayers. The basic physical picture is the same in these various theories, namely that the MR results from a coherent interplay of spin-dependent scattering mechanism occurring at the interfaces or in the bulk of the successive ferromagnetic layers. We calculated the conductance per period and magnetoresistance for an infinite multilayer in both cases of bulk and interfacial spin-dependent scattering. The results are found to be extremely close in the former case while larger differences (of the order of 15% in relative value) exist in the later case. Nevertheless this comparison supports the use of this type of semi-classical theories to interpret experimental data of spin-valve magnetoresistance.