Abstract
Yb and valence-band photoemission spectra of the first-order valence-transition compound have been measured with hard x ray at an excitation energy of 5.95 keV. Abrupt changes are clearly observed in both spectra around the transition temperature , in comparison with ultraviolet and soft x-ray photoemission (VUV-PES and SX-PES) spectra. From the Yb spectra, the Yb valence has been estimated to be from 220 down to 50 K and at 30–10 K. We propose that Yb hard x-ray photoemission spectroscopy is a very powerful method to estimate the valence of Yb with high accuracy. On the other hand, the -derived peaks in the valence-band spectra exhibit a remarkable enhancement below . The shape of the valence-band spectra is different from those of the VUV-PES and SX-PES spectra above , reflecting the In and contributions.
- Received 31 May 2004
DOI:https://doi.org/10.1103/PhysRevLett.93.246404
©2004 American Physical Society