Characterization of spin relaxation anisotropy in Co using spin pumping

Abstract

Ferromagnets are believed to exhibit strongly anisotropic spin relaxation, with relaxation lengths for spin longitudinal to magnetization significantly longer than those for spin transverse to magnetization. Here we characterize the anisotropy of spin relaxation in Co using the spin pumping contribution to Gilbert damping in noncollinearly magnetized Py${}_{1-x}$Cu${}_x$/Cu/Co trilayer structures. The static magnetization angle between Py${}_{1-x}$Cu${}_x$ and Co, adjusted under field bias perpendicular to film planes, controls the projections of longitudinal and transverse spin current pumped from Py${}_{1-x}$Cu${}_x$ into Co. We find nearly isotropic absorption of pure spin current in Co using this technique; fits to a diffusive transport model yield the longitudinal spin relaxation length $<2$ nm in Co. The longitudinal spin relaxation lengths found are an order of magnitude smaller than those determined by current-perpendicular-to-planes giant magnetoresistance measurements, but comparable with transverse spin relaxation lengths in Co determined by spin pumping.

6 pages, 5 figures

References in corpus (5)

• Spin convertance at magnetic interfaces
• Spin pumping damping and magnetic proximity effect in Pd and Pt spin-sink layers
• Wavenumber-dependent Gilbert damping in metallic ferromagnets
• Enhancement of the Gilbert damping constant due to spin pumping in noncollinear ferromagnet/nonmagnet/ferromagnet trilayer systems
• Damping of Confined Modes in a Ferromagnetic Thin Insulating Film: Angular Momentum Transfer Across a Nanoscale Field-defined Interface

Cited by in corpus (1)

• Measurement of spin mixing conductance in Ni${}_{81}$Fe${}_{19}$/$\alpha$-W and Ni${}_{81}$Fe${}_{19}$/$\beta$-W heterostrucutures via ferromagnetic resonance