One-dimensional ballistic transport with FLAPW Wannier functions

Hardrat, B.; Freimuth, F.; Mokrousov, Y.; Heinze, S.; Wang, N.

doi:10.1103/PhysRevB.85.245412

Journal Article

PreJuSER-22139

One-dimensional ballistic transport with FLAPW Wannier functions

Hardrat, B. ; Wang, N. ; Freimuth, F.FZJ* ; Mokrousov, Y.FZJ* ; Heinze, S.

2012
APS College Park, Md.

Physical review / B 85(24), 245412 (2012) [10.1103/PhysRevB.85.245412]

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Please use a persistent id in citations: http://hdl.handle.net/2128/10856 doi:10.1103/PhysRevB.85.245412

Abstract: We present an implementation of the ballistic Landauer-Buttiker transport scheme in one-dimensional systems based on density functional theory calculations within the full-potential linearized augmented plane-wave (FLAPW) method. In order to calculate the conductance within the Green's function method, we map the electronic structure from the extended states of the FLAPW calculation to Wannier functions, which constitute a minimal localized basis set. Our approach benefits from the high accuracy of the underlying FLAPW calculations, allowing us to address the complex interplay of structure, magnetism, and spin-orbit coupling and is ideally suited to study spin-dependent electronic transport in one-dimensional magnetic nanostructures. To illustrate our approach, we study ballistic electron transport in nonmagnetic Pt monowires with a single stretched bond including spin-orbit coupling, and in ferromagnetic Co monowires with different collinear magnetic alignment of the electrodes with the purpose of analyzing the magnetoresistance when going from tunneling to the contact regime. We further investigate spin-orbit scattering due to an impurity atom. We consider two configurations: a Co atom in a Pt monowire and vice versa. In both cases, the spin-orbit induced band mixing leads to a change of the conductance upon switching the magnetization direction from along the chain axis to perpendicular to it. The main contribution stems from ballistic spin scattering for the magnetic Co impurity in the nonmagnetic Pt monowire, and for the Pt scatterer in the magnetic Co monowire from the band formed from states with d(xy) and d(x2-y2) orbital symmetry. We quantify this effect by calculating the ballistic anisotropic magnetoresistance, which displays values up to as much as 7% for ballistic spin scattering and gigantic values of around 100% for the Pt impurity in the Co wire. In addition, we show that the presence of a scatterer can reduce as well as increase the ballistic anisotropic magnetoresistance.

Keyword(s): J

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Physics, Condensed Matter

Note: We acknowledge helpful discussions with S. Blugel. Funding by the DFG within the SFB677 is gratefully acknowledged. S. H. thanks the DFG for financial support under HE3292/8-1. N.-P.W. is grateful for financial support from The Natural Science Foundation of Zhejiang Province in China under Grant No. Y6100467. Y.M. and F. F. gratefully acknowledge the Julich Supercomputing Centre for computing time and funding under the HGF-YIG Programme VH-NG-513.

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