Spectral characterization of the Rashba spin-split band in a lead halide perovskite single crystal by photocurrent heterodyne interference spectroscopy

We characterized the temperature dependence of the complex dielectric susceptibility spectrum of a perovskite CH3NH3PbBr3 single crystal by using heterodyne interference spectroscopy. Owing to a time-domain measurement that is not influenced by incoherent lattice relaxations, we were able to detect a low-energy indirect-gap band. We observed two peaks in the energy region below the exciton transition at the R point in the imaginary part of the spectrum. The temperature dependences of the energies of these peaks were different from the dependence of the energy of the direct-transition exciton. The trends of both the splitting width and peak intensities can be explained by assuming a Rashba spin-split band.

Automated summary

Utilizing heterodyne interference spectroscopy, we investigated the temperature dependence of the complex dielectric susceptibility spectrum of a perovskite CH3NH3PbBr3 single crystal. We observed two peaks below the exciton transition at the R point in the imaginary part of the spectrum, with different temperature dependences compared to the direct-transition exciton energy. The trends in both splitting width and peak intensities can be explained by the presence of a Rashba spin-split band.