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MA: Fachverband Magnetismus
MA 30: Ultrafast Magnetization III
MA 30.12: Vortrag
Mittwoch, 18. März 2020, 12:30–12:45, HSZ 101
Ultrafast electrical signals generation using fs-laser pulses — •Bikash Das Mohapatra1, Wolfgang Hoppe1, Georg Woltersdorf1, and Georg Schmidt1,2 — 1Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 3, D-06120 Halle, Germany — 2Interdisziplinäres Zentrum für Meterialwissenschaften, Martin-Luther-Universität Halle-Wittenberg, Heinrich-Damerow-Straße 4, D-06120 Halle, Germany
Electronics are getting faster and it would be relevant to get signals from electronic devices in THz regime. Several methods to generate THz electromagnetic pulses[1] have been researched where ultrafast transverse charge current is generated from spin current by the ISHE. We investigate the ultrafast electrical response from waveguide structures with thermocouples illuminated by fs laser pulses. This can give new insight into the study of thermopower in electronic structures to convert temperature differences into electrical signals in the THz regime. Waveguide structures are used with Au/Pt thermocouples which are fabricated using Sputter deposition and e-beam lithography. When fs-laser is pumped into one of two thermocouples, it leads to a difference in temperature resulting in ultrafast thermovoltage due to the Seebeck Coefficient S=-ΔV/ΔT. The voltages are measured using a 50 GHz sampling oscilloscope. An alternative route is pursued by demagnetizing DC biased GMR structures by fs pulses to use the breakdown in resistance for electrical pulse generation. [1] T. Kampfrath et al. ,"Femtosecond formation dynamics of the spin Seebeck effect revealed by terahertz spectroscopy", Nat. Comm. 9, 2899 (2018).