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SU(4) Coherent Effects to the Canted Antiferromagnetic Phase in Bilayer Quantum Hall Systems at $ν$=2

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 SU$_{\text{spin}}$(2)$\otimes$SU$_{\text{ppin}}$(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.