Phys. Rev. Lett. Phys. Rev. A Phys. Rev. B Phys. Rev. C Phys. Rev. D Phys. Rev. E Phys. Rev. ST AB Rev. Mod. Phys. Phys. Rev. (Series I) Phys. Rev. Volume: Page/Article:

Phys. Rev. B 49, 368–377 (1994)

[Issue 1 – 1 January 1994 ]

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Effects of interfacial roughness on the magnetoresistance of magnetic metallic multilayers

Randolph Q. Hood and L. M. Falicov

Department of Physics, University of California, Berkeley, California 94720

Materials Sciences Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720

D. R. Penn

Electron Physics Group, National Institute of Standards and Technology, Gaithersburg, Maryland 20899

The Boltzmann equation is solved for a system consisting of a ferromagnetic–normal-metallic multilayer. The in-plane magnetoresistance of Fe/Cr and Fe/Cu superlattices is calculated for (1) varying interfacial geometric random roughness with no lateral coherence, (2) correlated (quasiperiodic) roughness, and (3) varying chemical composition of the interfaces. The interplay between these three aspects of the interfaces may enhance or suppress the magnetoresistance, depending on whether it increases or decreases the asymmetry in the spin-dependent scattering of the conduction electrons. Properties of the interfaces relevant to the giant negative magnetoresistance are discussed.

©1994 The American Physical Society

URL: http://link.aps.org/abstract/PRB/v49/p368
DOI: 10.1103/PhysRevB.49.368
PACS: 73.40.Jn, 73.50.Jt, 75.70.-i

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31. If the geometric random roughness of the interfaces were the only source of scattering, the prefactors in Eq. (11) must all be taken to be S _sigma =1. This is, however, not a realistic assumption. Impurities and other defects at the interfaces scatter electrons of opposite spin in a different way. Hence S_M and S_m are not equal, and in general both less than one.
32. It should be emphasized that ``roughness'' with a single, given periodicity, produces Bragg beams with well-defined directions of propagation, i.e., electron trajectories with their own (positive or negative) contribution to the current. For a smooth, nonuniform, quasiperiodic distribution of geometrical defects at the interface (i.e., a Fourier transform of the topography consisting of a peaked but continuous function), the distribution of velocities of electrons Bragg scattered over the Fermi surface tends to average down to zero, resulting in the electrons being effectively removed from the current-carrying distribution, i.e., relaxing back to equilibrium.
33. As in Eq. (7), the masses m_{i sigma} and m_{j sigma} in Eq. (12) are assumed to be equal. All calculations presented in the paper have m_{i sigma} =m, independent of the layer i and the spin sigma.

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