Session L15: Focus Session: Spins in Semiconductors - Spin Torque and Spin Injection
2:30 PM–5:30 PM, Tuesday, March 22, 2011
Room: D171
Sponsoring Units:
DMP GMAG FIAP
Chair: Roberto Myers, Ohio State University
Abstract ID: BAPS.2011.MAR.L15.3
Abstract: L15.00003 : Intrinsic spin-orbit coupling effects on spin and charge pumping in magnetic tunnel junctions with microwave-driven precessing magnetization
2:54 PM–3:06 PM
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Abstract 
Authors:
Farzad Mahfouzi
(Department of Physics and Astronomy, University of Delaware, Newark, DE 19711, USA)
Branislav Nikolic
(Department of Physics and Astronomy, University of Delaware, Newark, DE 19711, USA)
Naoto Nagaosa
(Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan)
We develop a microscopic quantum transport approach to the problem of spin pumping by precessing magnetization in one of the ferromagnetic layers within FIF or FIN (F-ferromagnet; N-normal metal; I-insulating barrier) magnetic tunnel junctions (MTJs) in the presence of intrinsic spin-orbit couplings (SOC) at the FI interface. Our approach evaluates the nonequilibrium Green functions (NEGFs) by starting from the time-dependent Hamiltonian of these junctions. To express the time-averaged charge current, or the corresponding dc pumping voltage in open circuits that was measured in recent experiments on MTJs [T. Moriyama {\em et al.}, Phys. Rev. Lett. {\bf 100}, 067602 (2008)], we construct a novel solution for the double-time-Fourier-transformed NEGFs where their two energy arguments are connected by the Floquet theorem describing emission and absorption of finite number of photons. Within this fully quantum-mechanical treatment of the conduction electrons, we find that only in the presence of the interfacial Rashba SOC non-zero dc pumping voltage in F$|$I$|$N junctions emerges at the adiabatic level (i.e., proportional to microwave frequency).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.MAR.L15.3