Critical Properties of a 2-D Frustrated Magnet With Non-Magnetic Impurities

We report on the classical Monte Carlo (MC) study of phase transitions (PTs) and critical behavior of a 2-D spin-pseudospin model describing a dilute magnet with competing charge and spin interactions. The static critical exponents of the specific heat and correlation length are calculated using the finite-size scaling theory in a wide range of model parameters. The order of PTs is analyzed within the energy histogram method. It is found that approaching the frustration point and increasing the density of non-magnetic impurities lead to non-universal critical behavior and first-order PTs. Features of non-universal critical behavior are shown to depend on the relationship between the parameters of the spin and pseudospin interactions.