Berlin 2018 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 6: Ultrafast magnetism I

MA 6.11: Vortrag

Montag, 12. März 2018, 12:15–12:30, EB 407

Steering of domain walls in Co/Fe₂₅Gd₇₅ bilayers by ultrashort laser pulses — •Yasser A. Shokr^1,2, Mustafa Erkovan³, Bin Zhang¹, Oliver Sandig¹, Matthias Bernien¹, Ahmet A. Ünal⁴, Florian Kronast⁴, Umut Parlak³, Jan Vogel⁵, and Wolfgang Kuch¹ — ¹Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany — ²Faculty of Science, Department of Physics, Helwan University, 17119 Cairo, Egypt — ³Sakarya University, Nanoscience and Nanoenginering Department, 54187 Sakarya, Turkey — ⁴Helmholtz-Zentrum Berlin für Materialien und Energie, 12489 Berlin, Germany — ⁵CNRS and Université Grenoble Alpes, Institut Néel, 38042 Grenoble, France

Steering magnetic domain walls by light is of high interest. We present a magnetic domain-imaging study by x-ray magnetic circular dichroism photoelectron emission microscopy on a Co/Fe₇₅Gd₂₅ bilayer under exposure to single focused ultrashort (100 fs) infrared laser pulses. Magnetic domain walls experience a force in the gradient of the laser pulses away from the center of the pulse, which can be used to move domain walls in a certain direction. Maximum domain-wall displacements close to 1 µm per laser pulse in zero external field are observed. Quantitative estimates show that electronic spin currents from the spin-dependent Seebeck effect are not strong enough to explain the effect, which we thus attribute to the torque exerted by magnons from the spin Seebeck effect that are reflected at the domain wall. The possibility to steer domain walls by ultrashort laser pulses might open new avenues for writing magnetic information.