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HL: Fachverband Halbleiterphysik

HL 8: Ultrafast Phenomena I

HL 8.2: Talk

Monday, March 18, 2024, 15:15–15:30, EW 015

Time-Domain Coherent Phononics in a Rashba Material — •Peter Fischer, Julian Bär, Moritz Cimander, Volker Wiechert, Alfred Leitenstorfer, and Davide Bossini — Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany

On the basis of spin-orbit coupling, the emerging research field of spintronics is exploring the possibility of using the spin of electrons instead of their charge as carrier of information. This fundamental interaction also enables the conversion of spin currents into charge currents and vice versa, crucial for linking spintronics and conventional electronics. The Rashba effect, an additional contribution to the spin-orbit coupling in materials lacking inversion symmetry, attracts particular attention in this context. We propose that the excitation of coherent phonons of a specific symmetry has the potential to modulate the bulk Rashba spin-orbit coupling and thus the spin-to-charge conversion efficiency on the ultrashort time scale. In our research, we focus on BiTeI, a layered semiconductor exhibiting a giant bulk Rashba effect. On this material, we perform systematic time-resolved pump-probe measurements of the transient reflectivity. The analysis of the acquired time traces confirms the successful excitation of the targeted coherent phonons at a frequency of 2.7 THz. Tuning the pump-photon energy into the visible, near-infrared and even mid-infrared spectral range, we disclose the most favorable conditions for optical generation of these lattice dynamics and thus, in perspective, for the manipulation of the bulk Rashba spin-orbit coupling.

Keywords: Spintronics; Coherent Phononics; Pump-probe experiment; Rashba effect; Time-Domain Spectroscopy