Meron deconfinement in the quantum Hall bilayer at intermediate distances

• Main Authors: Milovanovic, M. V, Dobardzic, E, Papic, Z
• Format: Journal Article
• Language: English
• Published: 29-12-2015
• Subjects: Physics - Mesoscale and Nanoscale Physics; Physics - Strongly Correlated Electrons
• DOI: 10.48550/arxiv.1509.01921

Phys. Rev. B 92, 195311 (2015) Quantum Hall bilayer phase diagram with respect to interlayer distance bears
a remarkable similarity with phase diagrams of strongly correlated systems as a
function of doping, with magnetic ordering on the one end and Fermi-liquid-like
behaviour on the other. Moreover, it has been suggested [PRL 101, 176803
(2008)] that a BCS correlated state of composite fermions with p-wave pairing
may exist in the intermediate region. In the same region, an exact
diagonalization study in the torus geometry [PRB 69, 045319 (2004)] pointed out
the existence of state(s) with pseudospin spiraling order. Here we reconcile
these two descriptions of the intermediate state by considering the underlying
bosonic representation of the composite fermion paired state in the long
distance limit, and by performing extensive exact diagonalizations on the
torus. We argue that the spiraling states belong to the manifold of degenerate
ground state(s), and are a consequence of Bose condensation of the
quasiparticles (with critical algebraic correlations) at non-zero momenta in
the two pseudospin states. The spiraling states, generated in this way as
spin-textures, can be identified with meron-antimeron constructions. Thus,
merons -- the fractionally charged vortex excitations of the XY magnetically
ordered state -- constitute some of the topological sectors. It follows that
merons are deconfined in the intermediate state, and allow for a smooth
transition between the magnetically ordered and Fermi-liquid-like phases, in
which they are bound in pairs.