Observation of Faraday magneto-optical rotation and near 90% spin polarization in CdSe microsheets at 1.6 K

Materials with strong magneto-optical properties contribute to developing next-generation spintronic and spin-photonic technologies. The study of the spin regulation of materials in magneto-optical systems can significantly improve information storage and processing capabilities. The low-dimensional nanostructures provide more options for manipulating spin degrees of freedom. This study used temperature-dependent photoluminescence (PL) spectroscopy to demonstrate the nonlinear effect of temperature on the PL behavior of the CdSe microsheet. The steady-state PL showed a near 90% spin polarization with the applied magnetic field at the low temperature of 1.6 K, indicating the presence of spin-polarized excitons. The CdSe microsheet grown along the [002] crystallographic direction suppressed spin relaxation and increased the spin diffusion length. The Faraday magneto-optical rotation was up to 3.979°/T in this magneto-optical measurement system. This study demonstrated the entire temperature-dependent magneto-optical polarization PL phase diagram, realizing a new method of magneto-optical control through low-dimensional nanostructures and laying the foundation for the spin photonic devices based on CdSe nanostructures.