Spin current driven Rabi oscillations in a ferromagnetic film

Abstract

Rabi oscillations describe the process whereby electromagnetic radiation interacts coherently with spin states in a non-equilibrium interaction so called the non-adiabatic regime [1]. Recently we have reported Rabi oscillations in an ultrathin layer of CoFeB [2]. There, the non-adiabatic regime was exited using a combination of femtosecond laser pulses and microwave excitations. In this work we take the non-adiabatic interaction in a magnetic medium a step further by replacing the microwave electromagnetic field with an oscillatory spin current that is generated by the spin Hall effect. Namely, spin current driven Rabi oscillation are demonstrated in a ferromagnet without the complications of driving an electromagnetic field. The demonstration marks another step in making the connection between concepts that are used in quantum information processing and apply them on the atomically engineered ferromagnetic systems. [1] M. Brik, N. Bernstein, and A. Capua, "Microwave and spin transfer torque driven coherent control in ferromagnets", ArXiv e-prints (2020) [2] A. Capua, C. Rettner, S.-H. Yang, T. Phung, and S. S. P. Parkin, "Ensemble-averaged Rabi oscillations in a ferromagnetic CoFeB film", Nature Commun. 8, 16004 (2017).