Dynamic exchange coupling and Gilbert damping in magnetic multilayers (invited)

Abstract

Temperature dependent magnetic properties of a Co ∕ Pd multilayer thin film J. Appl. Phys. 97, 10J105 (2005); 10.1063/1.1849671 Effects of nonlocal interlayer exchange in spin dynamics of a magnetic metal superlattice Low Temp. Phys. 24, 624 (1998); 10.1063/1.593648 Simple full micromagnetic model of exchange bias behavior in ferro/antiferromagnetic layered structures (abstract)We theoretically study dynamic properties of thin ferromagnetic films in contact with normal metals. Moving magnetizations cause a flow of spins into adjacent conductors, which relax by spin flip, scatter back into the ferromagnet, or are absorbed by another ferromagnet. Relaxation of spins outside the moving magnetization enhances the overall damping of the magnetization dynamics in accordance with the Gilbert phenomenology. Transfer of spins between different ferromagnets by these nonequilibrium spin currents leads to a long-ranged dynamic exchange interaction and collective excitation modes. Our predictions agree well with recent ferromagnetic-resonance experiments on ultrathin magnetic films.

dc effect in ferromagnetic resonance: Evidence of the spin-pumping effect?

“…A similar phenomenon has also been theoretically predicted by Brataas and co-workers, [2][3][4][5] in which they introduced the concept of the dc spin-current injection into arbitrary conductors with no net charge current. In 1999, Berger 1 theoretically proposed that a dc voltage would appear across a magnetic multilayer experiencing ferromagnetic resonance.…”

“…Figure 3 shows the dependence of the in-plane voltages as a function the thickness and composition of the spacer layer: tungsten, tantalum, and copper from top to bottom. [2][3][4][5] Our experimental measurements reveal that the intensity of the dc voltage shows an oscillatory behavior that falls off with increasing spacer-layer thickness. 1͑b͒.…”

Spin relaxation mechanism in a highly doped organic polymer film

“…The process of spin pumping dissipates the pure spin current into the PEDOT:PSS layer via the exchange interaction at the Py/PEDOT:PSS interface during the ferromagnetic resonance (FMR) excitation [15][16][17][18]. The transmitted spin current across the PEDOT:PSS layer is converted to the orthogonal electric field via the inverse spin Hall (ISH) effect in Pt [18][19][20].…”

First-principles study of magnetization relaxation enhancement and spin transfer in thin magnetic films

“…6 The spin-pumping concept for the magnetization dynamics of nanostructures has far-reaching consequences. It gives rise to an enhanced Gilbert damping of magnetic films in contact with conducting media, 4 may be employed as an FMR-operated spin battery, 7 and explains a dynamic exchange coupling in magnetic bilayers, 8,9 as well as a dynamic stiffness against current-induced magnetization reversal. 10 The analysis of experimental FMR probes of the magnetization dynamics in single films 5 and magnetic bilayers 8 relied on phenomenological models of the electronic structure.…”