Quantum spin pumping mediated by magnon
arXiv:1201.1947 · doi:10.1143/JPSJ.81.064717
Abstract
We theoretically propose quantum spin pumping mediated by magnons, under a time-dependent transverse magnetic field, at the interface between a ferromagnetic insulator and a non-magnetic metal. The generation of a spin current under a thermal equilibrium condition is discussed by calculating the spin transfer torque, which breaks the spin conservation law for conduction electrons and operates the coherent magnon state. Localized spins lose spin angular momentum by emitting magnons and conduction electrons flip from down to up by absorbing the momentum. The spin transfer torque has a resonance structure as a function of the angular frequency of the applied transverse field. This fact is useful to enhance the spin pumping effect induced by quantum fluctuations. We also discuss the distinction between our quantum spin pumping theory and the one proposed by Tserkovnyak et al.
27 pages, 2 figures. v2; the detail of the calculation has been added in Appendix. The distinction from the spin pumping theory proposed by Tserkovnyak et al. has been clarified in section 5. v3; typos corrected
References in corpus (8)
- Spin Transfer Torques
- Theory of magnon-driven spin Seebeck effect
- Microscopic approach to current-driven domain wall dynamics
- On A Proper Definition of Spin Current
- Microscopic Calculation of Spin Torques in Disordered Ferromagnets
- First-principles study of the spin-mixing conductance in Pt/NiFe junctions
- Spin Currents Induced by Nonuniform Rashba-Type Spin-Orbit Field
- A short note on spin pumping theory with Landau-Lifshitz-Gilbert equation under quantum fluctuation; necessity for quantization of localized spin