Optical access of spin-polarized excited states in Cs(PbMgZnCd)Br3 nanocrystals

The interplay of slow spin relaxation (long τ S ) and fast radiative recombination (short τ R ) is essential for using spin-polarized excited states in lead halide perovskites towards spintronics and quantum-optics technologies. Herein, we report on the observation of simultaneously long τ S (59.8 ps) and short τ R (3.4 ns) in the colloidal nanocrystals of high-entropy perovskites, Cs(PbMgZnCd)Br 3 , which enables the optical access and spin manipulation of excited states at room temperature. The incorporation of non-Pb metals spatially separates the [PbBr 6 ] 4− framework into smaller domains below the Bohr radius of excitons, and the size confinement leads to blue-shifted bright photoluminescence from short-lived photoexcitation species. Moreover, the distortion of [PbBr 6 ] 4− lattice is significantly enhanced in high-entropy structures, which enlarges the Rashba spin splitting and consequently prolongs τ S over an order of magnitude. Optical write-in and read-out of spin states via circularly polarized light are achieved for both photoluminescence and amplified spontaneous emission from Cs(PbMgZnCd)Br 3 . Optical Hanle effect is demonstrated and allows for very efficient spin manipulation (positive/negative polarizations ~25.8%) under a perpendicular magnetic field, showing the great potential of high-entropy perovskites for opto-spintronic applications.