Rotons in a hybrid Bose-Fermi system
I.A. Shelykh, T. Taylor, A.V. Kavokin
TL;DR
This paper investigates how interactions between excitons and electrons in a 2D hybrid system can lead to a roton minimum in the excitation spectrum, potentially causing superfluidity breakdown and affecting phase transition temperatures.
Contribution
It introduces a theoretical model showing the formation of a roton minimum due to exciton-electron interactions in a 2D system, revealing new mechanisms for superfluidity disruption.
Findings
Roton minimum can form in the excitation spectrum due to exciton-electron scattering.
The roton energy can drop below the ground state energy, indicating superfluidity breaking.
The BKT transition temperature decreases because of exciton-electron mediated attraction.
Abstract
We calculate the spectrum of elementary excitations in a two-dimensional exciton superfluid in the vicinity of a two-dimensional electron gas. We show that attraction of excitons due to their scattering with free electrons may lead to formation of a roton minimum. The energy of this minimum may go below the ground state energy which manifests breaking of the superfluidity. The Berezinsky-Kosterlitz-Thouless phase transition temperature decreases due to the exciton-exciton attraction mediated by electrons.
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