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HL: Fachverband Halbleiterphysik

HL 45: HL Posters III

HL 45.30: Poster

Donnerstag, 4. April 2019, 18:30–21:00, Poster E

Photoinduced transient spin polarization in the semiconducting lead halide perovskite (CH₃NH₃)PbI₃ above the orthorhombic-tetragonal phase transition — •Oskar Schuster¹, Daniel Niesner¹, Thomas Fauster¹, Shreetu Shrestha², Ievgen Levchuk², Miroslaw Batentschuk², and Christoph Brabec² — ¹Lehrstuhl für Festkörperphysik, Univ. of Erlangen–Nürnberg, Staudtstr. 7, D-91058 Erlangen — ²I-MEET, Univ. of Erlangen–Nürnberg, Martensstr. 7, D-91058 Erlangen

(CH₃NH₃)PbI₃ belongs to a class of semiconducting lead halide perovskites with singly degenerate valence and conduction band, playing an important role in current solar cell research. At 160 K the material undergoes a transition from a centrosymmetric orthorhombic phase to a tetragonal phase which is centrosymmetric on average, exhibiting local disorder. The concept of a "dynamical Rashba effect" induced by the local electric fields in the disordered structure has been proposed by theoretical models and by measurements of optically induced spin currents [1]. For the disordered, high–temperature phase a transient magneto–optical Kerr effect (MOKE) is induced by pumping the fundamental optical transition with circularly polarized light. A clear MOKE signal is absent in the ordered, low-temperature phase. This further supports the idea of a "dynamical Rashba effect". We discuss the picosecond spin dynamics and the possible spin scattering mechanisms in this new class of Rashba semiconductors.

[1] D. Niesner et al., Proc. Natl. Acad. Sci. 115, 9505 (2018)