Spin accumulation detected by Kerr effect

Context of project
​Kerr effect is a nonlinear optical effect named after its discoverer, John Kerr. When light travels in a medium a nonlinear polarization response occurs, which can provide useful information of the electric and magnetic fields of an specimen. Changes of intensity and polarization of light upon reflection are nowadays routinely use to characterize magnetic domains in magnetic sample, a well developed technique known as Kerr microscopy [1]. One ongoing challenge is to push the limits of sensitivity of Kerr microscopy and detect dynamic spin accumulation in nonmagnetic samples. This project aims at this very target with the aid of a bench-top time-resolved Kerr system [2].        

Kerr microscopy ref:
[1] aip.scitation.org/doi/10.1063/1.1150496
[2] aip.scitation.org/doi/10.1063/1.3053353 

Our work
We characterize the orientation of the non-equilibrium spin accumulation by a time resolved transverse magneto optical Kerr effect technique. We detect opposite orientation of spin polarization between the interfaces of Cu/Bi2O3 and Ag/Bi2O3, which directly elucidate their opposite initial spins configuration (sign of Rashba parameter). This study shows the feasibility of applying Kerr effect characterization to nonmagnetic metal systems with spatial inversion asymmetry. 

Read more:
​[1] Direct optical observation of spin accumulation at nonmagnetic metal/oxide interface
J. Puebla, F. Auvray, M. Xu, B. Rana, A. Albouy, H. Tsai, K. Kondou, G. Tatara, Y. Otani
Applied Physics Letters 111 (9), 092402 (2017), Editor's pick 
aip.scitation.org/doi/full/10.1063/1.4990113 
Personal contribution: Project leader (corresponding author), performed experiments, analyzed data, writing of manuscript

[2] Spin accumulation at nonmagnetic interface induced by direct Rashba–Edelstein effect
F Auvray, J Puebla, M Xu, B Rana, D Hashizume, Y Otani
Journal of Materials Science: Materials in Electronics 29 (18), 15664-15670 (2018)
link.springer.com/article/10.1007%2Fs10854-018-9162-5   
Personal contribution: Project leader (corresponding author), performed experiments