Berlin 2024 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 24: Terahertz Spintronics I
MA 24.13: Vortrag
Mittwoch, 20. März 2024, 12:45–13:00, EB 202
Terahertz detection of magneto-photocurrent in topological insulator Bi2Se3 — •Chihun In1,2, Genaro Bierhance1,2, Deepti Jain3, Tom Seifert1,2, Oliver Gueckstock1,2, Roberto Mantovan4, Seongshik Oh3, and Tobias Kampfrath1,2 — 1Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany — 2Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany — 3Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA — 4CNR-IMM Unit of Agrate Brianza, Via Olivetti 2, Agrate Brianza, MB 20864, Italy
Femtosecond laser excitation can drive ultrafast photocurrents in topological insulators (TIs) such as Bi2Se3. Here, we report THz emission from Bi2Se3 thin films by applying a magnetic field of |B|=0.3 T parallel to the film plane. First, we find a pronounced THz emission signal odd in B that changes its sign with B. Second, we observe a strong reduction of the THz amplitude as bismuth is substituted by indium. The reduced spin-orbit coupling strength of (Bi1−xInx)2Se3 removes the Dirac surface state at a critical concentration of x=0.07. Therefore, the suppressed THz signal of (Bi1−xInx)2Se3 for x>0.07 suggests that the Dirac surface state and spin-momentum locking are critical to the emergence of the observed THz magneto-photocurrent. The time dependence of the photocurrent will be extracted, and possible interpretations will be discussed.
Keywords: terahertz; topological insulator; spintronics; spectroscopy; ultrafast optics