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Conventional semiconductor physics

Conventional semiconductor physics, being one of the largest branches of solid state physics, studies both the fundamental principles of nature and the complexity of its systems. Semiconductors reflect the enormous diversity in phenomena and complexity in nature.

The research activity of our group in this field cover a wide spectrum of conventional low-dimensional semiconductor structures: from two-dimensional quantum wells (QWs) (e.g., CdTe/CdMgTe or GaInAs/GaAs) to zero-dimensional quantum dots (QDs) (e.g., GaAlAs/AlAs or CdTe/ZnTe), together with their doping of magnetic ions (e.g., Mn). We investigate these systems with the aid of various experimental techniques, which includes the optical spectroscopy, from microwaves up to visible spectral range (i.e., reflectance, transmission, photoluminescence, and photoluminescence excitation), and as well as the electronic transport. Both of them can be performed at low temperatures and (up to 40 mK) and application of an external magnetic field (up to 36 T, due to the recent capabilities of the LNCMI). We study the (fractional) quantum Hall effect and the structure of Landau levels in the QWs, the ladder of excitonic states in QDs, as well as the interactions between carriers (e.i., electron-phonon and electron-electron) and spin-dependent phenomena.

Quantum wells

Fractional quantum Hall effect in a dilute magnetic semiconductor We report the observation of the fractional quantum Hall effect in the lowest Landau level of a two-dimensional electron system (2DES), residing in the diluted magnetic semiconductor Cd1−xMnxTe. The presence of magnetic impurities results in a giant Zeeman splitting leading to an unusual ordering of composite fermion Landau levels. In experiment, this results in an unconventional opening and closing of fractional gaps (...)

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Quantum Dots

The excited spin-triplet state of a charged exciton in quantum dots We report on single-object spectroscopic studies of a characteristic set of three resonances which appear in GaAlAs/AlAs quantum dot structures. The experiments included the photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy, photon-correlation measurements, analysis of the linear polarization of the emission spectra as well as the PL and PLE spectroscopy performed as a function of magnetic field. (...)

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