[en] We discuss the current induced magnetization dynamics of spin valves F-0 vertical bar N vertical bar SyF where the free layer is a synthetic ferrimagnet SyF made of two ferromagnetic layers F-1 and F-2 coupled by RKKY exchange coupling. When the magnetic moment of the outer layer F-2 dominates the magnetization of the SyF, the sign of the effective spin torque exerted on the layer F-1 is controlled by the coupling's strength: for weak coupling the spin torque tends to antialign F-1's magnetization with respect to the pinned layer F-0. At large coupling the situation is reversed and tends to align F-1 with respect to F-0. At intermediate coupling, numerical simulations reveal that the competition between these two incompatible limits leads generically to spin torque oscillator (STO) behavior. The STO is found at zero magnetic field, with very significant amplitude of oscillations and frequencies up to 50 GHz or higher.
Disciplines :
Physics
Author, co-author :
Klein, Christian; CEA UJF Grenoble 1, SPSMS, INAC, UMR E 9001, F-38054 Grenoble, France.
Petitjean, Cyril ; Université de Liège - ULiège > Département de physique > Physique quantique statistique
Waintal, Xavier; CEA UJF Grenoble 1, SPSMS, INAC, UMR E 9001, F-38054 Grenoble, France.
Language :
English
Title :
Interplay between Nonequilibrium and Equilibrium Spin Torque Using Synthetic Ferrimagnets
Publication date :
2012
Journal title :
Physical Review Letters
ISSN :
0031-9007
eISSN :
1079-7114
Publisher :
Amer Physical Soc, College Pk, United States - Maryland
Volume :
108
Issue :
8
Pages :
086601-5
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
CEA CEA Eurotalent CE - Commission Européenne
Commentary :
We thank T. Rasing and W. Wulfhekel for very useful discussions. This work was supported by CEA NanoSim program, CEA Eurotalent, and EC Contract Macalo.
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