Spectroscopy of strongly correlated electrons in two-dimensional semiconductors

1. Developing optical technique for probing strongly correlated electronic states (Wigner crystals, fractional quantum Hall states as well as Chern insulators).

2. Optical spectroscopy of two-dimensional Landau-quantized electron and hole systems (including time-resolved measurements of spin-valley relaxation dynamics, Shubnikov-de Haas oscillations of optical conductivity).

Optical properties of semiconductor quantum dots

1. Effects of exchange interaction between confined carriers.

2. Dynamics of excitation and recombination of excitonic complexes.

3. Light-matter coupling in a system of quantum dot coupled to optical microcavity.

Optical spectroscopy of quantum dots doped with single transition metal ions:

1. Effects of s,p-d exchange interaction between carriers and a single magnetic ion.

2. Optical manipulation of a single ion spin.
3. Spin relaxation dynamics and coherent-related phenomena.

Research Highlights

Direct optical signature of the electronic

 Wigner crystal

If the strength of interactions between the electrons in 2D semiconductor exceeds their kinetic energy, the electrons form a spatially-ordered, Wigner crystal state. Here we provide a direct evidence for the emergence of this elusive state of matter using a novel optical technique that relies on the observation of exciton umklapp scattering in the periodic potential generated by the electrons forming the crystal.

T. Smoleński et al.,  Nature 595, 53-57 (2021)

Shubnikov-de Haas oscillations of the exciton resonance in a TMD monolayer

Upon the application of a strong magnetic field, the electronic bands of a TMD monolayer break up into a sequence of equidistant Landau levels. Here we demonstrate that the energy and linewidth of the exciton interacting with such a Landau-quantized electron system is sensitively-dependent on the Landau level filling factor thus exhibiting a prominent Shubnikov-de Haas oscillations. 

T. Smoleński et al., PRL 123, 097403 (2019)