title: Quadrupolar phases of the s=1 bilinear-biquadratic Heisenberg model on the triangular lattice.
abstract: Using mean-field theory, exact diagonalizations, and SU(3) flavor theory, we have precisely mapped out the phase diagram of the S = 1 bilinear-biquadratic Heisenberg model on the triangular lattice in a magnetic field, with emphasis on the quadrupolar phases and their excitations. In particular, we show that ferroquadrupolar order can coexist with short-range helical magnetic order, and that the antiferroquadrupolar phase is characterized by a remarkable 2/3 magnetization plateau, in which one site per triangle retains quadrupolar order while the other two are polarized along the field. Implications for actual S=1 magnets are discussed.
authors.affiliation: Institut Romand de Recherche Numérique en Physique des Matériaux (IRRMA), CH-1015 Lausanne, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Läuchli
authors.forename: Frédéric
authors.initials: F
authors.lastname: Mila
authors.forename: Karlo
authors.initials: K
authors.lastname: Penc