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arXiv · 1101.4302

Quantum Criticality without Tuning in the Mixed Valence Compound beta-YbAlB4

Yosuke Matsumoto·Satoru Nakatsuji·Kentaro Kuga·Yoshitomo Karaki·Naoki Horie·Yasuyuki Shimura·Toshiro Sakakibara·Andriy H. Nevidomskyy·Piers Coleman
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Abstract

Fermi liquid theory, the standard theory of metals, has been challenged by a number of observations of anomalous metallic behavior found in the vicinity of a quantum phase transition. The breakdown of the Fermi liquid is accomplished by fine-tuning the material to a quantum critical point using a control parameter such as the magnetic field, pressure, or chemical composition. Our high precision magnetization measurements of the ultrapure f-electron based superconductor β-YbAlB4 demonstrate a scaling of its free energy indicative of zero-field quantum criticality without tuning in a metal. The breakdown of Fermi-liquid behavior takes place in a mixed-valence state, in sharp contrast with other known examples of quantum critical f-electron systems that are magnetic Kondo lattice systems with integral valence.

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Yosuke Matsumoto, Satoru Nakatsuji, Kentaro Kuga, Yoshitomo Karaki, Naoki Horie, Yasuyuki Shimura, Toshiro Sakakibara, Andriy H. Nevidomskyy, Piers Coleman. 2011-01-22. Quantum Criticality without Tuning in the Mixed Valence Compound beta-YbAlB4. https://doi.org/10.1126/science.1197531

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