Signatures of electron-magnon interaction in charge and spin currents through magnetic tunnel junctions: A nonequilibrium many-body perturbation theory approach

We develop a numerically exact scheme for re-summing certain classes of Feynman diagrams in the self-consistent perturbative expansion for the electron and magnon self-energies in the non-equilibrium Green function formalism applied to a coupled electron-magnon (em) system driven out of equilibrium...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2014-07, Vol.90 (4), Article 045115
Main Authors: Mahfouzi, Farzad, Nikolić, Branislav K.
Format: Article
Language:English
Subjects:
Charge
Condensed matter
Electric current
Electronics
Feynman diagrams
Mathematical analysis
Signatures
Spintronics
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Summary:We develop a numerically exact scheme for re-summing certain classes of Feynman diagrams in the self-consistent perturbative expansion for the electron and magnon self-energies in the non-equilibrium Green function formalism applied to a coupled electron-magnon (em) system driven out of equilibrium by the applied finite bias voltage. Our scheme operates with the electronic and magnonic GFs and the corresponding self-energies viewed as matrices in the Keldysh space, rather than conventionally extracting their retarded and lesser components, which greatly simplifies translation of diagrams into compact mathematical expressions and their computational implementation. We also demonstrate that the sum of electronic spin currents in all of the semi-infinite leads attached to the active region quantifies the loss of spin angular momentum carried away from the active region by the magnonic spin current.
ISSN:1098-0121
1550-235X
DOI:10.1103/PhysRevB.90.045115