Electronic structure of YbGa1.15Si0.85 and YbGaxGe2-x probed by resonant x-ray emission and photoelectron spectroscopies

Yamaoka Hitoshi

Jarrige Ignace

Tsujii Naohito

Imai Motoharu

Lin Jung-Fu

Matsunami Masaharu

Eguchi Ritsuko

Arita Masashi

Shimada Kenya

Namatame Hirofumi

Taniguchi Masaki

Taguchi Munetaka

Senba Yasunori

Ohashi Haruhiko

Hiraoka Nozomu

Ishii Hirofumi

Tsuei Ku-Ding

Physical Review B

We performed an x-ray spectroscopic study combining resonant x-ray emission spectroscopy (RXES) and photoelectron spectroscopy on the superconducting ternary silicide YbGa_<1.15>Si_<0.85> and nonsuperconducting ternary germanide YbGa_xGe_<2-x> (x = 1.0 and 1.1). The Yb valence for all three compounds is found to be about 2.3. In YbGa_<1.15>Si_<0.85> no temperature dependence of the Yb valence is observed in the RXES spectra in the temperature range of 7-300 K, while the valence shows a drastic increase under pressure from the Yb^<2+> state partially including itinerant electrons to the localized Yb^<3+> state. Differences are observed in the valence-band spectra of the photoelectron spectroscopy between YbGa_<1.15>Si_<0.85> and YbGa_xGe_<2-x>, which may be attributed to the difference of crystal structure. We conclude that both the crystal structure of the planar GaSi layer in YbGa_<1.15>Si_<0.85> and the resultant electronic structure may have a crucial role in the occurrence of superconductivity.

Physics [ 420 ]

eng

The American Physical Society

Copyright (c) 2011 The American Physical Society

[ISSN] 1098-0121

[DOI] 10.1103/PhysRevB.83.104525

[NCID] AA11187113

[DOI] http://dx.doi.org/10.1103/PhysRevB.83.104525