Strain Wave Induced Extremely High Frequency Spin Resonance

Abstract

The interaction between the strain and the spin has recently received renewed interest in both scientific and technological communities. If the strain couples and modifies the spin, the magnetization of the materials can be manipulated, and even switched. This provides the possibility of realizing sub-picosecond magnetization switching stimulated by ultra-short picosecond strains. Here we experimentally report the manipulation of a magnetization via sub-picosecond strain waves, which are generated by ultrafast laser pulses. We then theoretically investigate the physical mechanisms of strain-spin coupling. We utilized the sub-picosecond acoustic strain waves (ASW) to modulate the magnetization dynamics of a technologically relevant material with perpendicular magnetic anisotropy (PMA) in Co/Pd multilayers. We observed a coherent magnetization resonance phenomenon around the cross-point of the frequencies of the ASW and spin precession. Our findings are relevant for the foundational research of the strain-spin coupling dynamics by ultrafast optical approaches as well as for the technological application of magnetization switching for future memory devices.