3D-Heisenberg magnetic coupling in the skyrmion system Fe^sub 1.5-x^Co^sub x^Rh^sub 0.5^Mo^sub 3^N (x=0.5,1.0,1.2)

Critical behaviors of Fe1.5-xCoxRh0.5Mo3N (x=0.5,1.0,1.2) are investigated, which are well known as a new family hosting skyrmion phase. The critical exponents β γ and δ which correspond to the magnetization, are obtained by the modified Arrott plot and critical isothermal analysis. The reliability of these critical exponents are testified by the Widom scaling law and scaling equation. The critical exponents of Fe1.5-xCoxRh0.5Mo3N (x=0.5,1.0,1.2) are close to the universality class of 3D-Heisenberg model, which suggests that the magnetic coupling in this system is of an isotropic short-range type.