title: Unveiling the nature of three-dimensional orbital ordering transitions: the case of e(g) and t(2g) models on the cubic lattice.
abstract: We perform large scale finite-temperature Monte Carlo simulations of the classical e(g) and t(2g) orbital models on the simple cubic lattice in three dimensions. The e(g) model displays a continuous phase transition to an orbitally ordered phase. While the correlation length exponent ν ≈ 0.66(1) is close to the 3D XY value, the exponent η ≈ 0.15(1) differs substantially from O(N) values. At T(c) a U(1) symmetry emerges, which persists for T < T(c) below a crossover length scaling as Λ ∼ ξ(a), with an unusually small a ≈ 1.3. Finally, for the t(2g) model we find a first order transition into a low-temperature lattice-nematic phase without orbital order.
authors.affiliation: Institute of Theoretical Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Sandro
authors.initials: S
authors.lastname: Wenzel
authors.forename: Andreas M
authors.initials: AM
authors.lastname: Läuchli