Time-domain detection of current controlled magnetization damping in Pt/Ni81Fe19 bilayer and determination of Pt spin Hall angle

Abstract

The effect of spin torque from the spin Hall effect in Pt/Ni81Fe19 rectangular bilayer film was investigated using time-resolved magneto-optical Kerr microscopy. Current flow through the stack resulted in a linear variation of effective damping up to ±7%, attributed to spin current injection from the Pt into the Ni81Fe19. The spin Hall angle of Pt was estimated as 0.11 ± 0.03. The modulation of the damping depended on the angle between the current and the bias magnetic field. These results demonstrate the importance of optical detection of precessional magnetization dynamics for studying spin transfer torque due to spin Hall effect. We gratefully acknowledge financial support from Department of Science and Technology, Government of India and the British Council for the DST-UKIERI joint project, Grant No. DST/INT/UK/P-44/2012. A.B. acknowledges financial support from DST under Grant No. SR/NM/NS-09/2011(G).