Berlin 2012 – scientific programme

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MA: Fachverband Magnetismus

MA 48: PhD Student Symposium: "Spintronics on the Way to modern Storage Technology II", Organization: "Univ. Mainz team"

MA 48.2: Topical Talk

Thursday, March 29, 2012, 13:30–14:00, BH 243

Spin-transfer processes: Magnetic coupling, spin-transfer torque, and pure spin currents — •Daniel E. Bürgler — Peter Grünberg Institute, Electronic Properties (PGI-6) and Jülich-Aachen Research Alliance, Fundamentals of Future Information Technology (JARA-FIT), Forschungszentrum Jülich, D-52425 Jülich, Germany

Modern magnetic storage technology relies on manipulating and detecting magnetization states of nanometer-sized ferromagnetic (FM) entities. Spin-transfer processes in FM/non-FM/FM structures give rise to spintronic concepts featuring such functionalities. Equilibrium spin-transfer without net spin or charge transport is the origin of (anti)ferromagnetic interlayer coupling, which played a key role for the discovery of giant magnetoresistance. A spin-polarized current, i.e. flow spin momentum and charge, exerts a torque on the magnetization when entering a FM material by transferring spin angular momentum from the current to the magnetization. These spin-transfer torques give rise to current-driven magnetization dynamics with unprecedented properties like magnetization reversal without applying an external field or the excitation of persistent large-angle magnetization precessions with frequencies in the GHz range, which are the basis for spin-transfer nano-oscillators. Pure spin currents, finally, transport spin momentum without net motion of charge. This situation results for instance from spin accumulation in a non-magnetic metal. Non-local transport measurements in lateral spin valve exploit spin accumulation to generate and detect pure spin currents. Devices based on pure spin currents potentially operate with significantly reduced dissipation.