Non-Fermi-liquid (NFL), a significant deviation from Fermi-liquid theory, usually emerges near an order-disorder phase transition at absolute zero. Recently, a diverging susceptibility toward zero temperature was observed in a quasicrystal (QC). Since an electronic long-range ordering is normally absent in QCs, this anomalous behaviour should be a new type of NFL. Here we study high-resolution partial-fluorescence-yield x-ray absorption spectroscopy on Yb-based intermediate-valence icosahedral QCs and cubic approximant crystals (ACs), some of which are new materials, to unveil the mechanism of the NFL. We find that for both forms of QCs and ACs, there is a critical lattice parameter where Yb-valence and magnetism concomitantly exhibit singularities, suggesting a critical-valence-fluctuation-induced NFL. The present result provides an intriguing structure-property relationship of matter; size of a Tsai-type cluster (that is a common local structure to both forms) tunes the NFL whereas translational symmetry (that is present in ACs but absent in QCs) determines the nature of the NFL against the external/chemical pressure.
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http://dx.doi.org/10.1038/s41598-020-74124-7 | DOI Listing |
J Phys Condens Matter
June 2023
Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
We have successfully grown single crystals of a novel ytterbium-based layered compoundYb4RuGe8and studied its structural, magnetic, thermal, and transport properties. The magnetic susceptibility has a broad peak caused by the Kondo effect at approximately40 Kand is enhanced below15 Kowing to the development of additional magnetic correlations. An analysis with the grand-Kadowaki-Woods relation reveals that the low-temperature state except for the effect of the additional magnetic correlations is a heavy-mass Fermi liquid.
View Article and Find Full Text PDFJ Phys Condens Matter
June 2022
Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7, Canada.
Sci Rep
October 2020
Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan.
Non-Fermi-liquid (NFL), a significant deviation from Fermi-liquid theory, usually emerges near an order-disorder phase transition at absolute zero. Recently, a diverging susceptibility toward zero temperature was observed in a quasicrystal (QC). Since an electronic long-range ordering is normally absent in QCs, this anomalous behaviour should be a new type of NFL.
View Article and Find Full Text PDFJ Phys Condens Matter
November 2017
RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
Electronic structures of ferromagnetic heavy fermion Yb compounds of YbPdSi, YbPdGe, and YbPtGe are studied by photoelectron spectroscopy around the Yb 4d-4f resonance, resonant x-ray emission spectroscopy at the Yb L absorption edge, and density functional theory combined with dynamical mean field theory calculations. These compounds all have a temperature-independent intermediate Yb valence with large [Formula: see text] and small [Formula: see text] components. The magnitude of the Yb valence is evaluated to be YbPtGe [Formula: see text] YbPdGe [Formula: see text] YbPdSi, suggesting that YbPtGe is the closest to the quantum critical point among the three Yb compounds.
View Article and Find Full Text PDFSci Rep
July 2017
Institute of Solid State Physics, Vienna University of Technology, 1040, Wien, Austria.
A pressure-induced anomalous valence crossover without structural phase transition is observed in archetypal cubic YbCu based heavy Fermion systems. The Yb valence is found to decrease with increasing pressure, indicating a pressure-induced crossover from a localized 4f state to the valence fluctuation regime, which is not expected for Yb systems with conventional c-f hybridization. This result further highlights the remarkable singularity of the valence behavior in compressed YbCu-based compounds.
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