Valence Transition of YbInCu4 Observed in Hard X-Ray Photoemission Spectra

Sato Hitoshi

Shimada Kenya

Arita Masashi

Hiraoka Koichi

Kojima Kenichi

Takeda Yukiharu

Yoshikawa Kunta

Sawada Masahiro

Nakatake Masashi

Namatame Hirofumi

Taniguchi Masaki

Takata Yasutaka

Ikenaga Eiji

Shin Shik

Kobayashi Keisuke

Tamasaku Kenji

Nishino Yoshinori

Miwa Daigo

Yabashi Makina

Ishikawa Tetsuya

Physical Review Letters

Yb 3d and valence-band photoemission spectra of the first-order valence-transition compound YbInCu4 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 TV = 42 K, in comparison with ultraviolet and soft x-ray photoemission (VUV-PES and SX-PES) spectra. From the Yb 3d spectra, the Yb valence has been estimated to be ~2.90 from 220 down to 50 K and ~2.74 at 30–10 K. We propose that Yb 3d hard x-ray photoemission spectroscopy is a very powerful method to estimate the valence of Yb with high accuracy. On the other hand, the Yb2+ 4f-derived peaks in the valence-band spectra exhibit a remarkable enhancement below TV. The shape of the valence-band spectra is different from those of the VUV-PES and SX-PES spectra above TV, reflecting the In 5s and 5p contributions.

ytterbium alloys

indium alloys

copper alloys

X-ray photoelectron spectra

mixed valence compounds

valence bands

eng

American Physical Society

Copyright (c) 2004 The American Physical Society.

[ISSN] 0031-9007

[DOI] 10.1103/PhysRevLett.93.246404

[NCID] AA00773679

[DOI] http://dx.doi.org/10.1103/PhysRevLett.93.246404