Spin transport parameters in Py/Ru and Py/Ta bilayers

J. E. GÓMEZ; B. ZERAI TEDLLA; N. R. ÁLVAREZ; G. ALEJANDRO; E. GOOVAERTS; A. BUTERA

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

Ridge, NY APS.

Lugar: NEW YORK; Año: 2014 vol. 90 p. 184401 - 184409

0163-1829

We present a systematic study of the spin transport properties in two different bilayer systems, Py/Ru and Py/Ta, combining ferromagnetic resonance (FMR) and inverse spin Hall effect (ISHE) voltage measurements. We have estimated the effective spin mixing conductance g_m by analyzing the permalloy (Py) thickness dependence of the FMR linewidth obtaining g_m = (3.8 ± 0.7) x 10^15 cm-2 and g_m = (1.3 ± 0.4) x 10^15 cm-2 for Py/Ru and Py/Ta, respectively. Analyzing the Ta thickness dependence of the ISHE voltage, we have been able to extract the spin diffusion length, LSD = 1.5 ± 0.5 nm, and spin Hall angle, QSH = -0.03 ± 0.01, of Ta. From the two series of Py/Ta bilayers - with thickness variation of ferromagnetic and nonmagnetic layers, respectively - we demonstrate a path to estimate the spin diffusion length from the experimental data, independent of the spin Hall angle and the microwave field amplitude.