Dynamics of polarized magnetoluminescence of localized excitons in mixed GaSe-GaTe crystals

Abstract

Polarization of radiation of triplet localized excitons induced by an external magnetic field in uniaxial GaSe-GaTe solid solutions (Voigt geometry) has been investigated using the time-resolved spectroscopy method. The linear radiation polarization occurring in a magnetic field is caused by a different behavior of radiation components polarized with E ‖ B and E ⊥ B (π- and σ-components, respectively). Under steadystate conditions of excitation by unpolarized light, the π-component intensity increases in the field, whereas the σ-component intensity gradually decreases with increasing field. It has been shown that the dependences of the π- and σ-component intensities I _π(B, t) and I _σ(B, t) on the magnetic field significantly change for the lifetime t of excited states. The different decay rates of π- and σ-components lead to the strong time dependence of the linear polarization of exciton radiation induced by a magnetic field. The degree of linear radiation polarization at the exciton luminescence band maximum in fields B ≥ 0.4 T at long times t approaches unity. A theoretical description of the observed dependences I _π(B, t) and I _σ(B, t) has been proposed. The fine structure parameters and lifetimes of triplet excitons in different spin states have been determined by comparing the theory and experiment.