Nonpareil Yb Behavior in YbMn 6 Ge 6 − x Sn x
2013; American Physical Society; Volume: 111; Issue: 9 Linguagem: Inglês
10.1103/physrevlett.111.096402
ISSN1092-0145
AutoresThomas Mazet, D. Malterre, Manuel François, C. Dallera, M. Grioni, G. Monaco,
Tópico(s)Iron-based superconductors research
ResumoWe investigate the temperature dependence of the Yb valence in ${\mathrm{YbMn}}_{6}{\mathrm{Ge}}_{1.8}{\mathrm{Sn}}_{4.2}$ and ${\mathrm{YbMn}}_{6}{\mathrm{Ge}}_{1.6}{\mathrm{Sn}}_{4.4}$ using resonant inelastic x-ray scattering experiments. Yb is found to be in an intermediate valent state in the whole investigated temperature range (10--450 K). We thus prove that the unusually high magnetic ordering temperature of Yb ($\ensuremath{\sim}60$ and 90 K for $x=4.2$ and 4.4, respectively) involves an intermediate valent Yb, an unprecedentedly observed phenomenon. Further, an anomalous increase in the Yb valence is observed upon cooling. A scenario is proposed to explain this unusual behavior. It is based on the presence of magnetically ordered Mn moments and on an Anderson Hamiltonian with a Zeeman term modeling the magnetic interactions.
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