FisMat2017 - Submission - View

Abstract's title: Pairing gap in the BCS-BEC crossover in a symmetric electron-hole bilayer with valley degeneracy
Submitting author: Gaetano Senatore
Affiliation: Università degli studi di Trieste
Affiliation Address: Strada Costiera 11, 34151, Trieste
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations: S. De Palo (CNR-IOM DEMOCRITOS, Istituto Officina dei Materiali, Via Bonomea 265, I-34136 Trieste, Italy; Dipartimento di Fisica, Universita` di Trieste, strada Costiera 11, 34151 Trieste, Italy) S. Moroni (CNR-IOM DEMOCRITOS, Istituto Officina dei Materiali, and SISSA Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, I-34136 Trieste, Italy)
Abstract

The realization of systems of spatially separated electrons and holes, in the search of the equilibrium excitonic condensate foreseen by [1], has gone on for more than two decades, but so far the condensate has eluded experimental detection [2]. It has been recently suggested that a substantial enhancement of the electron-hole attraction, to favour the condensate, could be obtained in coupled graphene bilayers [3]; a couple of experimental realizations has promptly followed [4]. Such systems have a quadratic energy dispersion on a wide density range and a twofold valley degeneracy in each bilayer.

We have performed calculations for an electron-hole bilayer with mass symmetry and twofold valley degeneracy (in each layer), to partially mimic the situation encountered in the coupled graphene bilayers proposed in [3]. Our goal is to provide estimates of the pairing gap for the electron-hole bilayer investigating the qualitative and quantitative effects of the valley degeneracy.

 

[1] Yu. E. Lozovik and V. I. Yudson, JETP Lett. 22, 274 (1975).


[2] See, e.g., J. A. Seamons et al.,  Phys. Rev. Lett. 102, 026804 (2009) and references therein.

[3] A. Perali, D. Neilson, and A. R. Hamilton, Phys. Rev. Lett. 110, 146803 (2013).


[4] J. I. A. Li, T. Taniguchiet al.,Phys. Rev. Lett. 117, 046802 (2016);  K. Lee et al.,Phys. Rev. Lett. 117, 046803 (2016).