Estimation of the spontaneous magnetization and the universal curve in MnCo1−<i>x</i>Nb<i>x</i>Ge alloys with long-range interactions

Abstract

We report on the critical behavior, spontaneous magnetization, and universal curve of MnCo1−xNbxGe alloys. Results demonstrate that the replacement of Co by Nb produces a decrease in the Curie temperature, TC, from 259.3 K to 240.3 K. Critical exponents obtained by the modified Arrott plot technique, Kouvel-Fisher method, and critical isothermal analysis are close to the theoretical prediction of the mean-field model values, revealing the characteristic of long-range ferromagnetic interactions. The values of spontaneous magnetization Msp estimated from |ΔSM| vs. M2 plots are in good agreement with the classical extrapolation from the Arrott curves, proving the validity and usefulness of this approach to estimate the Msp. Moreover, the experimental magnetic entropy changes measured for different fields collapse onto a universal curve, confirming the universal behavior of the magnetocaloric effect in this system.