Title: Rashba Effect in Hybrid Organic-Inorganic Perovskites: From Fundamentals to Devices

Abstract: Recent efforts in the utilization of quantum materials not only focus on a catalog of quantum coherent materials but increasingly seek new physical phenomena arising from the quantum properties of diverse materials. The interplay of many-body spin interactions in these materials (e.g., topological insulators, 2D materials, etc.) provides immense opportunities for quantum computing. The Rashba effect – a prototypical quantum phenomenon in crystalline materials–has revolutionized the field of spintronics by entailing a wide exploration of novel Rashba materials, and by envisioning the building of next-generation pure spin current generators, transmitters, and detectors, an enabler of quantum information technology. Solution-processed hybrid organic-inorganic perovskites (HOIPs) are prime candidates for exploring the potential Rashba effect, which is induced by the heavy metal and halogen atoms in a hybrid crystal structure with presumable inversion symmetry breaking. Having a strong Rashba effect, high charge mobility, and facile solution-based processing, HOIPs hold great promise as a new family of Rashba materials. In this talk, we will (i) provide experimental evidence that the surface Rashba effect occurs in prototypical 3D-HOIP, i.e., CH 3 NH 3 PbBr 3 single crystal at room temperature which depends on local symmetry breaking induced by specific surface termination. We demonstrate this using a suite of spatially resolved and depth-sensitive techniques, including circular photogalvanic effect, photoinduced inverse spin Hall effect, and multi-photon microscopy; and is supported by first-principle calculations. (ii) We will show the spintronic- THz radiation in 2D-HOIPs interfaced with a ferromagnetic metal, produced by the transient spin current under femtosecond laser excitation and ultrafast spin-to-charge conversion benefiting from the pronounced Rashba effect in the 2D-HOIPs. Our results offer new routes for studying interconversion between photons, charges and spins in solution-processed hybrid compounds, enabling their promising applications for future spin-dependent photodetectors and low-cost THz emitters.

Host: Thomas Schäefer