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MA: Fachverband Magnetismus

MA 59: Topological Insulators II (jointly with DS, HL, O, TT)

MA 59.1: Vortrag

Freitag, 24. März 2017, 09:30–09:45, HSZ 04

Laser induced DC photocurrents in a Topological Insulator thin film — •Nina Meyer¹, Thomas Schumann¹, Eva Schmoranzerová², Helena Reichlová³, Gregor Mussler⁴, Petr Nemec², Detlev Grützmacher⁴, and Markus Münzenberg¹ — ¹Institute of Physics, Ernst-Moritz-Arndt University, Greifswald, Germany — ²Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic — ³Institute of Physics ASCR v.v.i., Prague, Czech Republic — ⁴Inst. for Semiconductor Nanoelectronics, Peter Grünberg Institute-9, Forschungszentrum Jülich, Germany

Recent experiments indicate that the optical excitation of spin-polarized surface states of topological insulators (TI) can launch electron currents along the surface. The current’s direction can be controlled by varying the polarization of the driving light. We investigated if the spin-polarized current can be optimized by changing the angle of incident and the position of the laser spot on the sample. The used TI (Bi, Sb)₂Te₃ thin films with a thickness of 20 nm were structured to Hall bar devices. We successfully generated a photocurrent by illuminating the TI thin films with laser light whose polarization changes periodically. Analyzing the contributions of the photocurrent we detected a spin-polarized current. We found that the spin-polarized current is near-constant for angles of incident between 35^∘ and 65^∘ and that the position of the laser spot on the sample affects the spin-polarized current more than the angle of incident.
We acknowledge funding through DFG priority program SPP "Topological Insulators" and DAAD PPP Czech Republic "FemtomagTopo".