New Origin For Spin Current And Current-Induced Spin Precession In Magnetic Multilayers

Abstract

In metallic ferromagnets, an electric current is accompanied by a flux of angula r momentum, also called spin current. In multilayers, spatial variations of the spin current correspond to drive torques exerted on a magnetic layer. These torq ues result in spin precession above a certain current threshold. The usual kind of spin current is associated with translation of the spin-up and spin-down Ferm i surfaces in momentum space. We discuss a different kind of spin current, assoc iated with expansion and contraction of the Fermi surfaces. It is more nonlocal in nature, and may exist even in locations where the electrical current density is zero. It is larger than the usual spin current, in a ratio of 10 or 100, and is dominant in most cases. The new spin current is proportional to the differenc e Delta-mu = 0.001 eV between spin-up and spin-down Fermi levels, averaged over the entire Fermi surface. Conduction processes, spin relaxation, and spin-wave emission in the multilayer can be described by an equivalent electrical circuit resembling an unbalanced dc Wheatstone bridge. And Delta-mu corresponds to the output voltage of the bridge.

5 pages, 3 figures. To appear in J. Appl. Phys., vol. 89, May 15, 2001

References in corpus (2)

• Current-driven Magnetization Reversal and Spin Wave Excitations in Co/Cu/Co Pillars
• The Role of Spin-Dependent Interface Scattering in Generating Current-Induced Torques in Magnetic Multilayers

Cited by in corpus (18)

• Spin Transfer Torques
• Anatomy of Spin-Transfer Torque
• Mechanisms of spin-polarized current-driven magnetization switching
• Field dependence of magnetization reversal by spin transfer
• A self-consistent treatment of non-equilibrium spin torques in magnetic multilayers
• Identification of transverse spin currents in noncollinear magnetic structures
• Controlled normal and inverse magnetoresistance and current-driven magnetization switching in magnetic nanopillars
• Interaction Of Electrons With Spin Waves In The Bulk And In Multilayers
• The steady state in noncollinear magnetic multilayers
• Colossal electroresistance in ferromagnetic insulating state of single crystal Nd${}_0.7$Pb${}_0.3$MnO${}_3$
• Impurity Scattering of Wave Packets on a Lattice
• Influence Of Current Leads On Critical Current For Spin Precession In Magnetic Multilayers
• Current induced spin flip scattering at interfaces in noncollinear magnetic multilayers
• Magnetization reversal and current hysteresis due to spin injection in magnetic junction
• Inverted current-driven switching in Fe(Cr)/Cr/Fe(Cr) nanopillars
• Different steady states for spin currents in noncollinear multilayers
• General Form of Magnetization Damping: Magnetization dynamics of a spin system evolving nonadiabatically and out of equilibrium
• Spin torque due to diffusive spin current in magnetic texture