Magneto-Optical study of Bound Excitons in Semimagnetic Quantum Ring

Embedding magnetic impurity ions, like Mn2+, within semiconductor nanostructures has been a promising approach for magnetic tuning of the electronic states which are well illustrated in the present magneto-optical study of bound excitons in a

CdTe/Cd1-xMnxTe Quantum Ring (QR). The Giant Zeeman Splitting (GZS)[1,2] between the s + and s- Excitonic transitions in the Faraday configuration, due to the magnetic exchange interaction (sp-d exchange) between the localized substitutional magnetic impurity ions and the delocalized charge carriers, has been investigated for various concentration (x) of the magnetic ions, using the variational technique in the effective mass approximation invoking mean-field theory with the inclusion of modified Brillouin function. The enhancement of GZS, and in turn, the effective Landé g-factor with the application of magnetic field (g) is strikingly manifested in Type I –Type II transition in the band structure, as ‘g tremendously reduces the potential barrier height in the valence band as compared to the conduction band. This highlights the extraordinary magneto-optical properties including Giant Faraday Rotation (GFR)[3]. The results are discussed and compared in all the three magnetic regimes: (i) low ‘x’ at all T, (ii) arbitrary ‘x’ at high T, and (iii) large ‘x’ at low T where the magnetic saturation occurs[4]. The obtained results show that the excitonic Zeeman splitting is large for low ‘x and T’ as compared to high ‘x and T’ where the possibilities for the manganese ions to form antiferromagnetic pairs is maximized.

[1] Charles, J Barrows et. al, J. Phys. Chem. Lett. 2015, 6, 3076-3081.

[2] Chi, Li et. Al., J. Am. Chem. Soc. 2020, 142, 20616-20623.

[3] Seongmin, Ju et. al, Phys. Status Solidi A 2019, 1800549 (1-7).

[4] Bartholomew, D U et. al., Phys. Rev. B 1986, 34, 6943-6950.