Critical Behavior in the Fe-Based Antiperovskite Compound AlC1.1Fe3

In this study, the critical behavior of the Fe-based carbide antiperovskite compound AlC1.1Fe3 has been presented. There is a second-order phase transition and the magnetic state will change from ferromagnetic state to paramagnetic state near Curie temperature. Critical exponents (beta, gamma, delta) representing different significance of magnetism are obtained by separate classical methods, which are exceedingly agreeable with the mean-field model theory, indicating that magnetic behavior of AlC1.1Fe3 is dominated by long-range ferromagnetic coupling. According to the scaling equation m = f +/- (h), the experimental data obtained by the two experimental methods roughly overlap on the two curves, which demonstrates the reliability of these fitting parameters, and the convergence of the parameters also conforms to the mean-field model. Besides, the mutual exchange distance J(r) decreases as r(-4.695) due to the competitive Fe-Fe metal bond and Fe-C covalent bond. We suggest that the competition between the localized metal bond magnetic interaction and itinerant covalent bond hybridization should be responsible for the critical behavior of AlC1.1Fe3.