Signature of f-electron conductance in $\alpha$-Ce single-atom contacts

TL;DR

This study investigates the conductance properties of single-atom cerium contacts, revealing that the alpha phase exhibits enhanced conductance likely due to 4f electron contributions, advancing understanding of f-electron effects in nanoscale systems.

Contribution

It provides the first experimental evidence linking 4f electron contributions to conductance in single-atom cerium contacts, especially in the alpha phase.

Findings

Enhanced conductance observed in alpha-Ce single-atom contacts

Strong correlation between alpha-Ce fraction and conductance plateau

Attribution of conductance enhancement to 4f electron contribution

Abstract

Cerium is a fascinating element exhibiting, with its different phases, long-range magnetic order and superconductivity in bulk form. The coupling of the 4f electron to sd conduction electrons and to the lattice is responsible for unique structural and electronic properties like the isostructural first-order solid-solid transition from the cubic $\gamma$ phase to the cubic $\alpha$ phase, which is accompanied by a huge volume collapse of 14 %. While the $\gamma - \alpha$ phase transition has been investigated for decades, experiments aiming at disentangling the 4f contribution to the electric conductance of the different phases have not been performed. Here we report on the strongly enhanced conductance of single-atom Ce contacts. By controlling the content of $\alpha$-Ce employing different rates of cooling, we find a strong correlation between the fraction of $\alpha$-Ce and the magnitude of the last conductance plateau before the contact breaks. We attribute the enhanced conductance of $\alpha$-Ce to the additional contribution of the 4f level.