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Influence of large currents on the magnetization dynamics of ferromagnetic metals

Influence of large currents on the magnetization dynamics of ferromagnetic metals. J. Fernandez-Rossier , M. Braun and A. H. MacDonald Department of Physics, University of Texas at Austin. Current flow: How does it affect Magnetization dynamics ?. Magnetization controls

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Influence of large currents on the magnetization dynamics of ferromagnetic metals

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  1. Influence of large currents on the magnetization dynamics of ferromagnetic metals J. Fernandez-Rossier, M. Braun and A. H. MacDonald Department of Physics, University of Texas at Austin Current flow: How does it affect Magnetization dynamics ? Magnetization controls current flow (GMR, TMR) March Meeting 2003, Austin (TX)

  2. Current driven spin wave instability • Y. Ji, C.L. ChienCond-mat/0210116 • M. Tsoi et al. E.B. Myers et al.,Science 285, 867 (1999).

  3. Bazaliy, Jones, Zhang. Fully polarized s-d model: Current • Valid for ALL metallic ferromagnets: Spin Current • Enhanced Spin Wave Damping: Dynamics: Landau-Lifshitz <-> spin waves This work:

  4. Our model • Hubbard Model • Itinerant d electrons • Partially polarized electrons • Generalize to LDSA

  5. q Ground state: Spin split bands Spin waves. No current No current Spin wave= Linear combination e-h pairs

  6. Current q Spin waves with current Total current: Spin current:

  7. Remarks • The extra term modifies the off-diagonal terms • in the action • Similar term in super-fluids with super-current • Microscopic derivation • Unrelated to Spin Torque

  8. eV) m ( w Spin Wave Damping Spin waves for iron 4 Gilbert Damping 2 Two magnon damping Two magnon damping 0 0 2 4 6 8 10 q (m-1)

  9. Conclusions • Spin wave spectrum of current driven ferromagnetic metals • Enhanced Damping Email: joaquin@physics.utexas.edu

  10. d EF D.O.S. D.O.S. Spin waves in the Hubbard model • Hubbard model: • Partially polarized • itinerant d-electrons

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