# Superfluidity of Dipolar Excitons in a Black Phosphorene Double Layer

## TL;DR

This paper investigates the superfluid behavior of dipolar excitons in black phosphorene double layers, deriving analytical spectra and analyzing how screening, anisotropy, and exciton parameters influence superfluidity and critical temperature.

## Contribution

It provides analytical expressions for exciton spectra in black phosphorene double layers and explores the anisotropic superfluid properties influenced by screening and material parameters.

## Key findings

- Superfluidity arises due to dipole-dipole repulsion in black phosphorene layers.
- Critical temperature increases with exciton concentration and interlayer separation.
- Superfluid properties are anisotropic and depend on exciton and material parameters.

## Abstract

We study the formation of dipolar excitons and their superfluidity in a black phosphorene double layer. The analytical expressions for the single dipolar exciton energy spectrum and wave function are obtained. It is predicted that a weakly interacting gas of dipolar excitons in a double layer of black phosphorus exhibits superfluidity due to the dipole-dipole repulsion between the dipolar excitons. In calculations are employed the Keldysh and Coulomb potentials for the interaction between the charge carriers to analyze the influence of the screening effects on the studied phenomena. It is shown that the critical velocity of superfluidity, the spectrum of collective excitations, concentrations of the superfluid and normal component, and mean field critical temperature for superfluidity are anisotropic and demonstrate the dependence on the direction of motion of dipolar excitons. The critical temperature for superfluidity increases if the exciton concentration and the interlayer separation increase. It is shown that the dipolar exciton binding energy and mean field critical temperature for superfluidity are sensitive to the electron and hole effective masses. The proposed experiment to observe a directional superfluidity of excitons is addressed.