Monte Carlo study of the critical properties of the three-dimensional 120° model

We report on large scale finite-temperature Monte Carlo simulations of the prototypical classical 120° or eg model for orbital ordering on the simple cubic lattice in three dimensions. Our study reveals a continuous phase transition to an orbitally ordered phase with unusual critical properties compared to standard magnetism. While the correlation length exponent ≈0:665 is close to the 3D XY value, the exponent η≈0:15 differs substantially from O(N) values. Our results are corroborated by simulation results from a discrete eg-clock model that we have defined.