118 research outputs found
Exciton-exciton interaction in transition-metal dichalcogenide monolayers
We study theoretically the Coulomb interaction between excitons in transition
metal dichalcogenide (TMD) monolayers. We calculate direct and exchange
interaction for both ground and excited states of excitons. The screening of
the Coulomb interaction, specific to monolayer structures, leads to the unique
behavior of the exciton-exciton scattering for excited states, characterized by
the non-monotonic dependence of the interaction as function of the transferred
momentum. We find that the nontrivial screening enables the description of TMD
exciton interaction strength by approximate formula which includes exciton
binding parameters. The influence of screening and dielectric environment on
the exciton-exciton interaction was studied, showing qualitatively different
behavior for ground state and excited states of excitons. Furthermore, we
consider exciton-electron interaction, which for the excited states is governed
by the dominant attractive contribution of the exchange component, which
increases with the excitation number. The results provide a quantitative
description of the exciton-exciton and exciton-electron scattering in
transition metal dichalcogenides, and are of interest for the design of
perspective nonlinear optical devices based on TMD monolayers.Comment: 10 pages, 6 figure
Rashba plasmon polaritons in semiconductor heterostructures
We propose a concept of surface plasmon-polariton amplification in the
structure comprising interface between dielectric, metal and asymmetric quantum
well. Due to the Rashba spin-orbit interaction, mimina of dispersion relation
for electrons in conduction band are shifted with respect to the maximum of
dispersion dependence for holes in -point. When energy and momentum
intervals between extrema in dispersion relations of electrons and holes match
dispersion relation of plasmons, indirect radiative transition can amplify the
plasmons; excitation of leaky modes is forbidden due to the selection rules.
Efficiency of the indirect radiative transition is calculated and design of the
structure is analysed.Comment: Published (4 pages + 3 figures), 2nd proof versio
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