Electron-electron interaction effects in magnetic layered structures

– We consider some peculiarities of the logarithmic electron-electron interaction corrections to conductivity, which can arise in magnetic quantum wells due to spin-splitting of energy levels. The matrix elements of Coulomb interaction include different screening contributions from spin-up and spin-down electrons, which can lead to anomalous behavior of the interaction constant when the width of a spin quantum well is changed. Our results explain qualitatively the physical origin of the recently observed anomalous behavior of the logarithmic term in electrical resistivity of Co/Cr/Ag/Co layered structures (Aliev F. G. et al., Phys. Rev. Lett., 78 (1997) 134). There has been a great interest recently in confined structures with magnetic and nonmagnetic materials, like metallic magnetic multilayers or magnetic tunnel junctions [1–4]. An important feature of such systems is the existence of spin quantum wells (SQWs), i.e., different quantum wells for electrons with opposite spin orientations. Although a lot of work has been done on transport properties of magnetic layered structures, the low-temperature regime, where quantum corrections due to weak localization and electron-electron interaction are important [5–7], is still not well understood [1, 8–10]. The main issue is related to an internal magnetic field which may suppress the localization corrections. However, nonvanishing localization corrections were observed, e.g., in percolating Ni films [10]. On the other hand, the available results on low-temperature transport properties of epitaxial iron films [9] can be explained by both localization and interaction corrections. As is well known, the electronelectron interaction corrections are weakly sensitive to magnetic field and therefore can be expected to play a significant role in magnetic materials [11]. (∗) Present address: Max-Planck-Institut für Mikrostrukturphysik Weinberg 2, D-06120 Halle, Germany.