The effect of $f$-$c$ hybridization on the $\gamma\rightarrow\alpha$ phase transition of cerium studied by lanthanum doping

TL;DR

This study investigates how lanthanum doping affects the $f$-$c$ hybridization and consequently suppresses the $ ext{γ} ightarrow ext{α}$ phase transition in cerium, combining experimental and theoretical approaches.

Contribution

It provides new insights into the role of $f$-$c$ hybridization weakening in the phase transition suppression through combined experimental and modeling methods.

Findings

La doping weakens $f$-$c$ hybridization.

Suppression of the phase transition correlates with reduced hybridization.

Results align with effects of other rare earth and actinide additions.

Abstract

The hybridization between the localized 4$f$ level ($f$) with conduction ($c$) states in $\gamma$-Ce upon cooling has been previously revealed in single crystalline thin films experimentally and theoretically, whereas its influence on the $\gamma\rightarrow\alpha$ phase transition was not explicitly verified, due to the fact that the phase transition happened in the bulk-layer, leaving the surface in the $\gamma$ phase. Here in our work, we circumvent this issue by investigating the effect of alloying addition of La on Ce, by means of crystal structure, electronic transport and ARPES measurements, together with a phenomenological periodic Anderson model and a modified Anderson impurity model. Our current researches indicate that the weakening of $f$-$c$ hybridization is the major factor in the suppression of $\gamma\rightarrow\alpha$ phase transition by La doping. The consistency of our results with the effects of other rare earth and actinide alloying additions on the $\gamma\rightarrow\alpha$ phase transition of Ce is also discussed. Our work demonstrates the importance of the interaction of $f$ and $c$ electrons in understanding the unconventional phase transition in Ce, which is intuitive for further researches on other rare earth and actinide metals and alloys with similar phase transition behaviors.