E138-03 - Forschungsbereich Functional and Magnetic Materials
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Journal:
Journal of Physics: Condensed Matter
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ISSN:
0953-8984
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Date (published):
2009
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Number of Pages:
9
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Publisher:
IOP PUBLISHING LTD
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Peer reviewed:
Yes
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Keywords:
Condensed Matter Physics; General Materials Science
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Abstract:
Crystal structure, specific heat, thermal expansion, magnetic susceptibility and electrical resistivity studies of the heavy fermion system CeNi9−xCuxGe4 (0≤x≤1) reveal a continuous tuning of the ground state by Ni/Cu substitution from an effectively fourfold-degenerate non-magnetic Kondo ground state of CeNi9Ge4 (with pronounced non-Fermi-liquid features) towards a magnetically ordered, effectively twofold-degenerate ground state in CeNi8CuGe4 with TN = 175 ± 5 mK. Quantum critical behavior, C/T\propto \chi \propto {-}\ln {T} , is observed for x\cong 0.4 . Hitherto, CeNi9−xCuxGe4 represents the first system where a substitution-driven quantum phase transition is connected not only with changes of the relative strength of the Kondo effect and RKKY interaction, but also with a reduction of the effective crystal field ground state degeneracy.
