Critical behavior of the second-order magnetic transition in LaFe_11.7-xCo_xSi_1.3C_0.15 alloys

The critical behavior of NaZn13-type LaFe11.7-xCoxSi1.3C0.15 (x = 0.7, 0.8, and 0.9) alloys is investigated in this study. For LaFe11.7-xCoxSi1.3C0.15 (x = 0.7, 0.8, and 0.9) alloys, the values of the maximum magnetic entropy change, delta|SM|(max), are proportional to the magnetic field, H-2/3. The reliable critical exponents, beta, gamma and delta are calculated. The value of gamma for LaFe11.7-xCoxSi1.3C0.15 obtained by using the modified Arrott plot method is 1.013, 1.023, and 0.980 for x = 0.7, 0.8, and 0.9, respectively. With an increase in the Co content, the LaFe11.7-xCoxSi1.3C0.15 (x = 0.7, 0.8, 0.9) alloys become far away from the first-order phase transition and the magnetic interaction changes from short-range to long-range below the Curie temperature.