Excitonic condensation in double-layer Phosphorene and GaAs double quantum well heterostructures

Date: 2 April 2019

Venue: Campus Groenenborger, Building U, Room 244 - Groeneborgerlaan 171 - 2020 Antwerpen (route: UAntwerpen, Campus Groenenborger)

Time: 4:00 PM - 5:00 PM

Organization / co-organization: CMT

Short description: CMT lecture presented by Samira Saberi-Pouya

Excitonic superfluidity in double phosphorene monolayers separated by h-BN layers is investigated using the BCS mean-field equations. We show that the superfluid gap function is anisotropic as a function of k. The anisotropy originates from the anisotropic electron mass in phosphorene monolayers. We find that the superfluid gap is approximately twice as large in the zigzag direction than in the armchair direction. This is due to the larger effective mass in the zigzag direction.

We determine the Kosterlitz-Thouless transition temperature with a maximum value of ∼ 90 K. This value suggests double electron-hole phosphorene monolayers as a system to observe anisotropic superfluidity at high temperature and accessible carrier densities. The transition temperatures are higher than the those predicted for double graphene bilayers. The anisotropy in the electron-hole superfluidity can be detected in Coulomb drag experiments by rotating one of the phosphorene sheets with respect to the other.

We have also studied excitonic superfluidity in GaAs/AlGaAs quantum well electron-hole heterostructures. We find that the densities and temperatures are close to those currently experimentally attainable.

Contact email: lucian.covaci@uantwerpen.be

Link: http://cmt.uantwerpen.be