Spin-transfer in bilayer magnetic nanopillars at high fields as a function of free layer thickness

Abstract

Spin transfer in asymmetric Co/Cu/Co bilayer magnetic nanopillars junctions has been studied at low temperature as a function of free-layer thickness. The phase diagram for current-induced magnetic excitations has been determined for magnetic fields up to 7.5 T applied perpendicular to the junction surface and free-layers thicknesses from 2 to 5 nm. The junction magnetoresistance is independent of thickness. The critical current for magnetic excitations decreases linearly with decreasing free-layer thickness, but extrapolates to a finite critical current in the limit of zero thickness. The limiting current is in quantitative agreement with that expected due to a spin-pumping contribution to the magnetization damping. It may also be indicative of a decrease in the spin-transfer torque efficiency in ultrathin magnetic layers.

5 Pages, 4 Figures

References in corpus (9)

• Microwave Oscillations of a Nanomagnet Driven by a Spin-Polarized Current
• Current-driven Magnetization Reversal and Spin Wave Excitations in Co/Cu/Co Pillars
• Nonlocal magnetization dynamics in ferromagnetic heterostructures
• Direct-Current Induced Dynamics in Co90Fe10/Ni80Fe20 Point Contacts
• Anatomy of Spin-Transfer Torque
• Current Induced Excitations in Cu/Co/Cu Single Ferromagnetic Layer Nanopillars
• Ferromagnetic resonance study of polycrystalline Cobalt ultrathin films
• Current-induced macrospin vs spin-wave excitations in spin valves
• The steady state in noncollinear magnetic multilayers

Cited by in corpus (11)

• Layer thickness dependence of the current induced effective field vector in Ta|CoFeB|MgO
• Magnetoresistance and spin-transfer torque in magnetic tunnel junctions
• Determination of Penetration Depth of Transverse Spin Current in Ferromagnetic Metals by Spin Pumping
• Charge pumping by magnetization dynamics in magnetic and semi-magnetic tunnel junctions with interfacial Rashba or bulk extrinsic spin-orbit couplings
• Critical current of spin transfer torque-driven magnetization dynamics in magnetic multilayers
• Co-resonant enhancement of spin-torque critical currents in spin-valves with synthetic-ferrimagnet free-layer
• Penetration Depth of Transverse Spin Current in Ferromagnetic Metals
• Dissipation due to pure spin-current generated by spin pumping
• Effective attraction induced by repulsive interaction in a spin-transfer system
• Nanofabrication of spin-transfer torque devices by a PMMA mask one step process: GMR versus single layer devices
• Dependence of critical current of spin transfer torque-driven magnetization dynamics on free layer thickness