Speaker
Description
We have studied the laser-induced magnetization dynamics of single-crystalline Gd(0001) thin films with time- and angle-resolved photoemission spectroscopy (tr-ARPES). Our earlier measurements showed a magnetic non-equilibrium in the valence bands [1,2], between the valence band and the 4f systems [3], and in the surface state [4]. All these measurements share a common excitation energy of 1.55 eV.
In a recent study performed at the Artemis Facility at the Rutherford Appleton Laboratory, we used a 0.95 eV pump and 36 eV probe pulse to record the band structure of single-crystalline Gd during laser-induced demagnetization.
We find an initial increase of the exchange splitting within the first 200 fs after excitation, which was also observed in MOKE experiments. The exchange splitting then decreases on the same time scale (0.8 ps) as in our previous experiments [2] despite the lower pump energy. In addition, we observe oscillations in the energetic position of the valence bands and the surface state before excitation. This effect was attributed to ponderomotive acceleration by a transient grating formed by the interference of the incoming and outgoing pump pulses [5].
References
[1] M. Teichmann, B. Frietsch, K. Döbrich, et al. , Phys. Rev. B 91 , 014425 (2015).
[2] R. Carley, K. Döbrich, B. Frietsch, et al. , Phys. Rev. Lett. 109 , 0574012 (2012).
[3] B. Frietsch, J. Bowlan, R. Carley, et al. , Nat. Commun. 6 , 8262 (2015).
[4] B. Andres, M. Christ, C. Gahl, et al. , Phys. Rev. Lett. 115 , 207404 (2015).
[5] U. Bovensiepen, S. Declair, M. Lisowski, et al. , Phys. Rev. B 79 , 045415 (2009).
