SU(4) coherent effects to the canted antiferromagnetic phase in bilayer quantum Hall systems at ν=2

Abstract

In bilayer quantum Hall (BLQH) systems at ν=2, three different kinds of ground states are expected to be realized, i.e. a spin polarized phase (spin phase), a pseudospin polarized phase (ppin phase) and a canted antiferromagnetic phase (C-phase). An SU(4) scheme gives a powerful tool to investigate BLQH systems which have not only the spin SU(2) but also the layer (pseudospin) SU(2) degrees of freedom. In this paper, we discuss an origin of the C-phase in the SU(4) context and investigate SU(4) coherent effects to it. We show peculiar operators in the SU(4) group which do not exist in SUspin(2)⊗SUppin(2) group play a key role to its realization. It is also pointed out that not only spins but also pseudospins are "canted" in the C-phase.

The study of Goldstone modes in ν = 2 bilayer quantum Hall systems

“…We need to know how the parameters α and β are expressed in terms of the physical variables. Form (22) it is trivial to see that…”

“…The ground state structure of the ν = 2 bilayer QH system has been investigated based on the SU(4) formalism [20,21,22,23,24,25]. The expectation values of the SU(4) isospin operators are the order parameters, in terms of which an anisotropic SU(4) nonlinear sigma model has been derived to describe low-energy coherent phenomena [20].…”