Dresden 2006 – wissenschaftliches Programm

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SYMS: Magnetic Switching

SYMS 1: Magnetic Switching I

SYMS 1.1: Hauptvortrag

Montag, 27. März 2006, 15:00–15:45, HSZ 04

Manipulation of magnetization by spin transfer: switching, microwave generation — •Albert Fert¹, O. Boulle¹, V. Cros¹, M. Elsen¹, J. Grollier¹, A. Hamzic¹, H. Jaffrés¹, M. AlHajDarwish², J. Bass², H. Kurt², W. P. Pratt², J. Barnas³, I. Gimtra³, I. Weymann³, R. Giraud⁴, G. Faini⁴, and A. Lamaitre⁴ — ¹Unité Mixte de Physique CNRS/Thales, 91767 Palaiseau, France — ²Michigan State University, East Lansing, MI, USA — ³Poznan University, Poland — ⁴LPN/CNRS, Marcoussis, France

The magnetization of a ferromagnetic body can be manipulated without applying any magnetic field, only by transferring some quantity of spin angular momentum from a spin-polarized electrical current. The first part of the lecture introduces the concept of spin transfer and describes basic experiments we performed on pillar-shaped metallic pillars and tunnel junctions. Specific experiments giving more insight on the microscopic mechanism will also be presented, for example experiments in which the switching currents can be inverted by the introduction of impurities with selected spin dependent scattering cross-section. The second part of the talk summarizes the theoretical model developed for the calculation of the spin torque and its application to several problems: inversion or tuning of the switching currents by impurity scattering, generation of microwave oscillations at zero field, etc. I will conclude with some work on the problem of the synchronization of spin transfer oscillators, an important challenge for the future applications to microwave generation.