Superfluidity in asymmetric electron-hole systems

TL;DR

This paper investigates superfluidity in asymmetric electron-hole systems with spatial separation, revealing that asymmetries can be compensated, allowing superfluid states over a range of parameters, including coexistence at zero temperature.

Contribution

It demonstrates that superfluidity can persist despite asymmetries in electron-hole systems and predicts the possibility of two critical temperatures and coexistence states.

Findings

Superfluid state exists over a wide asymmetry range.

Two critical temperatures can occur in the system.

Coexistence of normal and superfluid states at zero temperature.

Abstract

The pairing in a system of electrons and holes in two spatially separated parallel planes is studied in the case of electron-hole asymmetry caused by the difference in the carriers masses and their chemical potentials. It is found that the superfluid state is possible in a wide range of the asymmetry parameters, because the asymmetries can effectively compensate each other. It is predicted that the system may exhibit two critical temperatures for some asymmetry parameters. The lower critical temperature corresponds to the superfluid transition induced by thermal fluctuations. In the asymmetric system a coexistence of the normal and superfluid states is possible even at zero temperature.