Spin-dependent Raman and Brillouin light scattering on excitons in CsPbBr$_3$ perovskite crystals

TL;DR

This study investigates the spin properties of excitons and charge carriers in CsPbBr$_3$ perovskite crystals using spin-dependent light scattering, revealing detailed Zeeman effects, g-factor anisotropies, and new spin-flip mechanisms in magnetic fields.

Contribution

It provides new insights into spin-dependent scattering mechanisms, including the role of trions and double electron spin-flips, in CsPbBr$_3$ perovskite crystals.

Findings

Measured Zeeman splittings and g-factors of excitons and carriers.

Identified new spin-flip mechanisms involving trions and localized electrons.

Observed polarization-sensitive shifts in Brillouin scattering on exciton-polaritons.

Abstract

The spin properties of excitons and charge carriers in CsPbBr$_3$ lead halide perovskite crystals are investigated by spin-dependent light scattering in magnetic fields up to 10 T. Spin-flip Raman scattering spectra measured under resonant excitation of exciton-polaritons show a rich variety of features provided by the Zeeman splittings of excitons and of electrons and holes interacting with the excitons. The magnitudes and anisotropies of their Land\'e $g$-factors are measured. A detailed consideration of the responsible mechanisms is presented and discussed in relation to the experimental data, in particular on the polarization properties of the Raman spectra. We consider several mechanisms for the combined spin-flip Raman scattering processes involving resident carriers and photoexcited excitons and suggest new ones, involving trions in the intermediate scattering state. A double electron spin-flip caused by the exciton interaction with two localized or donor-bound electrons is revealed. The spectral lines of Brillouin light scattering on exciton-polaritons shift in energy and become polarization-sensitive in magnetic field, evidencing the splitting of the exciton-polariton dispersion.