Time Reversal Symmetric Topological Exciton Condensate in Bilayer HgTe Quantum Wells
Number of Authors: 3
2014 (English)In: Physical Review Letters, ISSN 0031-9007, Vol. 112, no 14, 146405- p.Article in journal (Refereed) Published
We investigate a bilayer system of critical HgTe quantum wells, each featuring a spin-degenerate pair of massless Dirac fermions. In the presence of an electrostatic interlayer Coulomb coupling, we determine the exciton condensate order parameter of the system self-consistently. Calculating the bulk topological Z(2) invariant of the resulting mean-field Hamiltonian, we discover a novel time reversal symmetric topological exciton condensate state, coined the helical topological exciton condensate. We argue that this phase can exist for experimentally relevant parameters. Interestingly, due to its multiband nature, the present bilayer model exhibits a nontrivial interplay between spontaneous symmetry breaking and topology: Depending on which symmetry the condensate order parameter spontaneously picks in combined orbital and spin space, stable minima in the free energy corresponding to both trivial and nontrivial gapped states can be found.
Place, publisher, year, edition, pages
2014. Vol. 112, no 14, 146405- p.
IdentifiersURN: urn:nbn:se:su:diva-105229DOI: 10.1103/PhysRevLett.112.146405ISI: 000335860800018OAI: oai:DiVA.org:su-105229DiVA: diva2:731868
FunderSwedish Research Council