Superfluidity of dipolar excitons in a transition metal dichalcogenide double layer

Abstract

We study formation and superfluidity of dipolar excitons in double layer heterostructures formed by two transition metal dichalcogenide (TMDC) atomically thin layers. Considering screening effects for an electron-hole interaction via the harmonic oscillator approximation for the Keldysh potential, the analytical expressions for the exciton energy spectrum and the mean field critical temperature ${T}_{c}$ for the superfluidity are obtained. It is shown that binding energies of $A$ excitons are larger than for $B$ excitons. The mean field critical temperature for a two-component dilute exciton system in a TMDC double layer is analyzed and shown that the latter is an increasing function of the factor $Q$, determined by the effective masses of $A$ and $B$ excitons and their reduced mass. Comparison of the calculations for ${T}_{c}$ performed by employing the Coulomb and Keldysh interactions demonstrates the importance of screening effects in TMDC.