Abstract-Terahertz dynamics of spins and charges in CoFe/Al2O3 multilayers

J. D. Costa, T. J. Huisman, R. V. Mikhaylovskiy, I. Razdolski, J. Ventura, J. M. Teixeira, D. S. Schmool, G. N. Kakazei, S. Cardoso, P. P. Freitas, Th. Rasing, and A. V. Kimel

Phys. Rev. B 91, 104407 – Published 12 March 2015

https://journals.aps.org/prb/abstract/10.1103/PhysRevB.91.104407

The ultrafast laser-induced response of spins and charges in CoFe/Al2O3 multilayers are studied using THz and optical pump-probe spectroscopies. We demonstrate the possibility of ultrafast manipulation of the transport and magnetic properties of the multilayers with femtosecond laser excitation. In particular, using time-resolved THz transmission experiments we found that such an excitation leads to a rapid increase of the THz transmission (i.e., electric resistivity). Our experiments also reveal that femtosecond laser excitation results in the emission of broadband THz radiation. To reveal the origin of the emitted THz radiation, we performed magnetic-dependent measurements of the THz emission. We also compared the observed electric field of the THz radiation to calculations performed using subpicosecond laser-induced demagnetization measurements. The good agreement between the experimentally obtained spectra and the calculations corroborates that the measured THz emission originates from the demagnetization process.

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