SKM 2021 – scientific programme

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MA: Fachverband Magnetismus

MA 11: Posters Magnetism III

MA 11.18: Poster

Wednesday, September 29, 2021, 13:30–16:30, P

THz-2D Scanning Spectroscopy — •Finn-Frederik Stiewe, Tobias Kleinke, Tristan Winkel, Ulrike Martens, Jakob Walowski, Christian Denker, and Markus Münzenberg — Institute of Physics, University Greifswald, Germany

THz-spectroscopy offers attractive imaging capabilities for scientific research, especially in life science. Its low photon energies lead to non-destructive interaction with matter [1,2]. However, wavelengths above 100 μm principally limit its spatial resolution by diffraction. Near-field-imaging using spintronic emitters offers the most feasible approach to overcome this restriction. In our study, we investigate THz-pulses generated by fs-laser-excitations in CoFeB/Pt heterostructures, based on spin currents together with a LT-GaAs Auston switch as detector. The spatial resolution is tested by applying a 2D scanning technique with motorized stages allowing scanning steps in the sub-micrometer range. For this purpose, the spintronic emitter is directly evaporated on a gold-test pattern separated by a several hundred nanometer thick insulating spacer layer. Moving these structures with respect to the THz wave generation spot allows for resolution determination using the knife-edge method. We observe a THz beam FWHM of 4.86 *0.37 μm at 1 THz by using near-field imaging, which are in the dimension of the laser spot. Due to its simplicity, our technical approach offers a large potential for wide-ranging applications.

Funding by: MetaZIK PlasMark-T (FKZ:03Z22C511), BMBF

[1] A. G. Davies et al., Materials Today, Vol. 11 (2008) 18. [2] A. Y. Pawar et al., Drug Invention Today, Vol. 5 (2013).