Monte Carlo study of the ordering of the pyrochlore Ising model with the long-range RKKY interaction

The ordering of the Ising model on a pyrochlore lattice interacting via the long- range RKKY interaction, which is intended to model a metallic pyrochlore magnet such as Pr2Ir2O7, is studied by Monte Carlo simulations. Depending on the parameter kF representing the Fermi wavevector, the model exhibits rich ordering behaviors. When the kF -value is close to the experimental value, the model exhibits a '2-in 2-out' local spin structure reminiscent of the spin ice accompanied by the antiferromagnetic Curie-Weiss constant. This observation is consistent with experiment. The model exhibits a first-order transition into the magnetic long-range ordered state without showing a spin-liquid-like behavior.