Nanoscale physics

On spintronic torque effect in multilayer magnetic nanostructures 
Korostil A.A1., Krupa M.M.1  

1Department of Physics of Meso- and Nanocrystalline Magnetic Structures, Institute of Magnetism NAS and MES  of Ukraine.  Vernadsky av., 36b, Kyiv, Ukraine. E-mail: amand@rambler.ru

Spintronics of multilayer magnetic nanostructures is based on the electric control and detection of localized magnetic states via the exchange interaction of the electric-induced spin current with localized magnetic moments. Regardless of the type of the magnetic exchange interaction (ferromagnetic (FM) or antiferromagnetic (AFM)), the impact on the localized magnetic states occurs via the spin torques exerting on the localized magnetic moments. In the FM and AFM cases, these spin torques can result in the FM and AFM order dynamics and switching, respectively. In the case of FM nanostructures it exhibits in the known giant magnetoresistance effect, which was applied for new kinds of field-sensing and magnetic memory devices [1, 2].  The spin torque effectiveness is determined by threshold spin current density for excitation of localized spins due to the nature of spin polarization. The spin polarization can be induced by the effective field of magnetic exchange interaction and magnetic field of spin-orbit interaction related and unrelated to spin polarized electron transport through interface to the localized magnetic states, respectively. The origin of the spin polarization and magnetic exchange interaction between localized magnetic states determines the time and spatial scales of the spin torque effects. The lasts are described in the framework of the microscopic tight-binding model involving the spin-orbit interaction, the interaction between free and localized magnetic states. 

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