Unveiling the (De)coupling of magnetostructural transition nature in magnetocaloric R5Si2Ge2 (R = Tb, Gd) materials

Abstract

We present a detailed study on the magnetization under high magnetic fields of Tb5Si2Ge2 and Gd5Si2Ge2 compounds. From the Arrott plot construction (A. Arrott, Phys. Rev. 108, 1394 (1957)), we were able to estimate the TC of each structure (M and O(I)) experimentally and found that the TC of the O(I) phase can be directly obtained by extrapolating the TC curve of this phase in the respective phase diagram. Using a physical model based on free energy considerations, one explains the (de)coupling of the magnetic and structural transitions in R5(SixGe1−x)4 (R = Tb, Gd) compounds.