Fermi level and phase transformations in GdCo$_2$

TL;DR

This study investigates phase transformations in GdCo_2 by measuring chemical potential, electrical resistance, and current flow, revealing multiple characteristic temperatures linked to structural and magnetic changes during heating.

Contribution

It provides a comprehensive experimental analysis of phase transformations in GdCo_2 using three independent methods, highlighting the non-smooth nature of heating in polycrystalline materials.

Findings

Identification of characteristic temperatures during heating

Evidence of structural and magnetic reordering processes

Chemical potential behavior correlates with phase changes

Abstract

We performed three independent measurements for a polycristalline, ferromagnetic $GdCo_2$ sample in the temperature range from 300-440 K: chemical potential, current flow through the $GdCo_2-polymer-reference$ $% metal$ sandwich and the conventional resistivity mesurement. In all the measurements we observed characteristic temperatures (irregular points) which were confirmed by these methods. It makes an evidence that plenty of transformation processes at heating of the sample take place (here: relative displacements of the $Gd$ and $Co$ ions, grain boundary and domain structure movements, magnetic reordering, etc.). They are not artifacts or experimental error but they rather visualize the fact that heating of a polycristalline material is not a smooth process. All of them clearly demonstrate the behaviour of the chemical potential with changing temperature.