Monte Carlo study of the critical properties of the three-dimensional120° model

Abstract

We report on large scale finite-temperature Monte Carlo simulations of the classical120° oreg orbital-only model on the simple cubic lattice in three dimensions with afocus towards its critical properties. This model displays a continuous phasetransition to an orbitally ordered phase. While the correlation length exponentν≈0.665 is close to the 3DXY value, the exponentη≈0.15 differs substantiallyfrom O(N) values. We also introduce a discrete variant of theeg model,called the eg-clock model, which is found to display the same set of exponents.Further, an emergent U(1) symmetry is found at the critical pointTc, which persists forT < Tc below a crossoverlength scaling as Λ ∼ ξa, withan unusually small a≈1.3.