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Raman Investigation of the Mn 2+ –Mn 2+ Interaction in Semimagnetic Semiconductor Quantum Wells
Author(s) -
Stühler J.,
Schaack G.,
Dahl M.,
Waag A.,
Landwehr G.,
Kavokin K. V.,
Merkulov I. A.
Publication year - 1996
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/(sici)1097-4555(199603)27:3/4<281::aid-jrs951>3.0.co;2-b
Subject(s) - raman scattering , raman spectroscopy , chemistry , exchange interaction , condensed matter physics , ion , semiconductor , quantum well , magnetic semiconductor , scattering , atomic physics , molecular physics , physics , optics , ferromagnetism , quantum mechanics , laser , organic chemistry
Isolated pairs of antiferromagnetically coupled Mn 2+ ions in Mn‐based semimagnetic semiconductors possess a series of energy levels whose separation is determined by their nearest‐neighbour exchange interaction. Raman transitions were observed between the S =0 ground state and the magnetically split S =1 levels of these pairs in Cd 1‐x Mn x Te/Cd 1‐y Mg y Te quantum well structures comprising semimagnetic quantum wells (Cd 1‐x Mn x Te) of different well widths and Mn concentrations. The Raman shift of the S =0→ S =1, M =0 transition shows a non‐negligible dependence on the Mn concentration, which is interpreted as an effect due to interaction of the Mn 2+ pair with more distant neighbours. A nearest‐neighbour exchange constant J NN =‐(6.11±0.15) K for Cd 1‐x Mn x Te is determined. Further, a model is presented for the scattering mechanism, where band‐edge states act as intermediate states in the scattering process owing to the strong exchange interaction between the carrier spin and the localized Mn 2+ ions. Confinement and localization effects in the quantum well, which produce strong gradients of the carrier wavefunction, play a decisive role for the intensity of the Mn 2+ pair Raman signals.