Sensing polarized light via switchable Rashba-Dresselhaus spin splitting in a ferroelectric semiconductor

Sensing the spin states of circularly polarized light (CPL) is a prerequisite for varied advanced applications. Here, we show that a Rashba-Dresselhaus (RD) spin-splitting mechanism is responsible for detecting CPL in noncentrosymmetric semiconductors. In ferroelectric (2FPMA)2PbBr4 (2FPMA = 2-fluorobenzylammonium), the polar structure and strong spin-orbit coupling trigger a large RD spin splitting that differentiates CPL-excited carriers in the momentum space via optical transition selection rules. A single-crystal-based device shows a comparable detection performance to sense CPL spin states with an asymmetric factor of 0.37. Furthermore, the electrical reversal of the ferroelectric polarization leads to switchable bulk photovoltaic effect and spin texture, enabling self-powered and tunable photodetection. This indicates the validity of the RD spin-splitting mechanism in directly sensing CPL spin states without the need for chirality, thereby expanding the research scope of electrically switchable spin-responsive materials.