Exciton magnetic polaron in CdTe/Cd_{1-x}Mn_{x}Te semimagnetic quantum ring

Abstract: Magnetically doped nanostructures can significantly enhance the interaction between the band carriers and the dopant atoms. Motivated by the demonstration of the enhanced sp-d exchange interaction in quantum confined structures with the increased stability of the exciton magnetic polaron (EMP), we report the quantitative and qualitative analyses of the EMP formation in CdTe/Cd_{1-x}Mn_{x}Te diluted magnetic quantum ring (QR). The QR with two different configurations: (i) the non-magnetic ring (CdTe) embedded in the semimagnetic Cd_{1-x}Mn_{x}Te matrix, and (ii) magnetically non-uniform quantum structures embedded with Mn2+ ions both in the ring and in the barrier regimes, have been investigated for various mole fractions of the Mn dopants. The larger polaron binding energy (EMP) of 23meV is estimated for the 5% molar Mn contents compared to the other quantum confined systems made of CdMnTe. The magnetic field dependence of the MP energy and the corresponding polaron parameters like exchange field, localization radius of the MP, and the degree of circular polarization induced by the external applied magnetic field at T = 4.2K have been derived. The obtained results are in excellent agreement with the trend of the significant degradation of EMP in an external magnetic field, and with the contradictory tendencies of EMP for the QR with configuration (i) and (ii), as reported from the time-integrated measurements based on selective excitation for the quantum systems made of CdMnTe and other DMS materials.