Nanoscale physics

Electron-hole Coulomb interaction and quantum states of the two-dimensional magnetoexcitons
Moskalenko S.A.1, Zubac I.1,2
1 Institute of Applied Physics. Academiei, 5, MD-2028, Republic of Moldova. 
2 The State University ”Dimitrie Cantemir”. Academiei, 3/2, MD-2028, Republic of Moldova; 1Institute of Applied Physics. Academiei, 5, MD-2028, Republic of Moldova.  Email:  ionzubac33@gmail.com

A new property of the 2D magnetoexciton is the interdependence between the center-of-mass and the relative e-h motions induced by the action of the Lorentz force. This interdependence happens to play an important role promoting to the formation of the Dirac cone dispersion law under the influence of the exchange e-h Coulomb interaction.
The symmetric magnetoexciton state due to the exchange e-h Coulomb interaction acquires a Dirac cone dispersion law in the range of small in-plane wave vectors with the group velocity  proportional to the magnetic field strength , with equal probabilities of the quantum transitions from the ground state of the crystal in both light circular polarizations but with maximum probability in the Faraday geometry of the light propagation and vanishing probability in the Voigt one [1]. In difference on it, the asymmetric superposition state remains with the usual dispersion law inherited from the bare magnetoexciton states and has dipole-active quantum transitions in both circular polarizations, indifferent on the direction of the light propagation. When the light is arbitrary propagating in 3D space, the symmetric superposition state is dipole active in the case of the linear polarization vector  with the longitudinal projection on the 2D exciton in-plane wave vector  and is forbidden in the linear light polarization with the vector , which has a transverse projection on . 

1.	Moskalenko, S. A., Podlesny, I. V., Zubac, I. A., Novikov, B. V. Two-dimensional magnetoexciton superposition states with Dirac cone dispersion law and quantum interference effects in optical transitions // Solid State Commun.-2020.-312.-P. 113714.