Electron-electron interaction effects in magnetic layered structures

Abstract

Abstract. -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][2][3][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][6][7], is still not well understood [1,[8][9][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:

Weak localization in ferromagnets with spin-orbit interaction

“…In this notation, the expressions for bare vertices Γ 0 ↑ and Γ 0 ↓ coincide with Eqs. (11) and (12), whereas for the spin-flip vertex Γ 0 sf we have…”

“…These include two theoretical works 10,11 and a few reports on experiments, [12][13][14][15][16][17] which prove the existence and importance of the quantum corrections related to both weak localization and electron-electron interaction effects. The theoretical description, however, was restricted to the effects of localization on the spin-density fluctuations in the vicinity of the ferromagnetic transition 10 and to electronelectron interaction effects in spin dependent quantum wells 11 . It is well known that the quantum corrections due to weak localization in nonmagnetic systems are suppressed by a sufficiently large magnetic induction B.…”