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.
@article{arxiv.1711.06659,
title = {Pressure dependence of Ce valence in CeRhIn5},
author = {Z. E. Brubaker and R. L. Stillwell and P. Chow and Y. Xiao and C. Kenney-Benson and R. Ferry and Z. Jenei and R. J. Zieve and J. R. Jeffries},
journal= {arXiv preprint arXiv:1711.06659},
year = {2018}
}