Pressure dependence of Ce valence in CeRhIn5

TL;DR

This study investigates how pressure affects the cerium valence in CeRhIn5 using x-ray absorption spectroscopy, revealing minimal changes up to 6 GPa and challenging existing valence fluctuation theories.

Contribution

It provides the first detailed pressure-dependent Ce valence measurements in CeRhIn5, setting upper limits and questioning the valence crossover predictions.

Findings

Ce valence remains stable up to 5.5 GPa at room temperature.

No significant valence change observed below 6 GPa at 22 K.

Results challenge the predicted valence crossover at 2.35 GPa.

Abstract

We have studied the Ce valence as a function of pressure in CeRhIn5 at 300 K and at 22 K using x-ray absorption spectroscopy in partial fluorescent yield mode. At room temperature, we found no detectable change in Ce valence greater than 0.01 up to a pressure of 5.5 GPa. At 22 K, the valence remains robust against pressure below 6 GPa, in contrast to the predicted valence crossover at P=2.35 GPa. This work yields an upper limit for the change in Ce-valence and suggests that the critical valence fluctuation scenario, in its current form, is unlikely.