Optical manifestation of magnetic polarons bound to excitons and resident holes in a (Cd,Mn)Te quantum well

Abstract

Photoluminescence and multiple ${\mathrm{Mn}}^{2+}$ spin-flip Raman scattering (SFRS) are studied in the (Cd,Mn)Te/(Cd,Mg)Te quantum well with excess resident hole concentration under resonance continuous-wave photoexcitation in the localized states of excitons and trions at $T=1.5$ K. A magnetic polaron shift of both exciton and trion photoluminescence is observed to be increasing with an increase in the magnetic field up to 6 T applied perpendicularly to the sample growth axis (Voigt geometry). Exciton magnetic polaron shift in magnetic field is attributed to the adiabatic energy transfer from the exchange reservoir to the Zeeman reservoir during the precession of the ${\mathrm{Mn}}^{2+}$ ions in the summary field of external magnetic and exchange hole fields. A mechanism of the magnetic polaron shift of trion photoluminescence is suggested. It is related to direct photoexcitation of the triplet trion state, which is stable in the conditions which are provided by the resident hole magnetic polarons. In these conditions, the ${\mathrm{Mn}}^{2+}$ magnetic moment experiences additional magnetization in the double exchange field provided by two holes in the triplet trion state. It is observed that the maximum efficiency of multiple ${\mathrm{Mn}}^{2+}$ spin-flip Raman scattering falls into the energy range corresponding to the states of localized excitons where the exciton magnetic polaron shift is observed. From this we conclude that the magnetic polaron state could be an intermediate state of the multiple ${\mathrm{Mn}}^{2+}$ SFRS process.