High temperature electron-hole superfluidity with strong anisotropic gaps in double phosphorene monolayers

TL;DR

This paper predicts highly anisotropic electron-hole superfluidity in double phosphorene monolayers, with high transition temperatures up to 90 K, offering promising directions for experimental realization of anisotropic condensate states.

Contribution

It introduces the first theoretical prediction of anisotropic superfluidity in double phosphorene monolayers with high transition temperatures.

Findings

Maximum superfluid gap in BEC regime along armchair direction

Transition temperature up to ~90 K

Higher than in graphene-based systems

Abstract

Excitonic superfluidity in double phosphorene monolayers is investigated using the BCS mean-field equations. Highly anisotropic superfluidity is predicted where we found that the maximum superfluid gap is in the BEC regime along the armchair direction and in the BCS-BEC crossover regime along the zigzag direction. We estimate the highest Kosterlitz-Thouless transition temperature with maximum value up to $\sim 90$ K with onset carrier densities as high as $4 \times 10^{12}$ cm$^{-2}$. This transition temperature is significantly larger than what is found in double electron-hole few-layers of graphene. Our results can guide experimental research towards the realization of anisotropic condensate states in electron-hole phosphorene monolayers.