Do we understand electron correlation effects in Gadolinium based intermetallic compounds?

TL;DR

This study investigates electron correlation effects in Gd-based intermetallic compounds, revealing unexpected resistivity behavior, heavy-fermion-like heat capacity, and magnetic field suppression, indicating complex electron interactions.

Contribution

It provides new insights into electron correlation effects in Gd alloys, challenging the assumption of weak correlations in f-electron systems.

Findings

Resistivity increases with decreasing temperature in some Gd alloys.

Magnetoresistance is large due to suppression of excess resistance by magnetic field.

Alloys exhibit heavy-fermion-like heat capacity behavior.

Abstract

Recognising the difficulties in systematic understanding of the physical characteristics of strongly correlated f-electron systems, we considered it worthwhile to subject the so-called "normal" f-electron systems like those of Gd to careful investigations. We find that the spin-disorder contribution to electrical resistivity ($\rho$) in the paramagnetic state, instead of remaining contant, surprisingly increases with decreasing temperature (T) in the paramagnetic state in some of the Gd alloys. In some cases, this "excess resistance" is so large that a distinct minimum in the plot of $\rho$ versus T can be seen, mimicking the behaviour of Kondo lattices. This excess resistance can be suppressed by the application of a magnetic field, naturally resulting in large magnetoresistance. In addition, these alloys are found to exhibit heavy-fermion-like heat-capacity behavior. These unusual findings imply hither-to-unexplored electron correlation effects even in Gd-based alloys.