Surface Acoustic Wave mediated magneto elastic investigation of magnetic thin film systems

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Surface Acoustic Waves (SAW) represent an unconventional and very sensitive tool for the characterization of thin magnetic films up to the GHz regime. Despite the expected stunning possibilities of SAW only few experiments have been carried out that demonstrated the possibility to dynamically control the spin system. In the present proposal, we will investigate exchange-biased ferromagnetic thin films prepared on piezoelectric LiNbO3 substrates. We plan to explore the magnetoelastic interaction with high frequency SAW giving rise to spin wave stimulation in the sub-GHz regime and influencing the magnetic reversal behavior. Another highly interesting material system for SAW studies are amorphous ferrimagnetic TbFe alloy thin films, which exhibit large values of magnetic anisotropy and magnetostriction. When exchange coupled to a ferromagnetic layer, the magnetization reversal is accompanied by the nucleation and annihilation of an interface domain wall. The reversal process including its magnetic domain structure under the impact of SAW interaction will be investigated. Furthermore, in ferrimagnetic rare earth transition metal alloy films, optically induced magnetization reversal induced by circularly polarized femtosecond laser pulses was recently discovered. In this case, the reversal direction of magnetization is determined solely by the helicity of the light and not by an external magnetic field. Here, we plan to study the stimulus of SAW on ultra-fast spin dynamics in combination with laser pulses. In such time-resolved investigations the built-in clock frequency of the SAW is very much beneficial to the experiment and permits virtually stroboscopic measurements of the underlying interaction.