T/B scaling of magnetization in the mixed valent compound β-YbAlB4

Abstract

Here we provide the first clear evidence of Fermi-liquid breakdown in an intermediate valence system. We employ high precision magnetization measurements of the valence fluctuating superconductor beta-YbAlB4 to probe the quantum critical free energy down to temperatures far below the characteristic energy scale of the valence fluctuations. The observed T/B scaling in the magnetization over three decades not only indicates unconventional quantum criticality, but places an upper bound on the critical magnetic field |B_c| < 0.2 mT, a value comparable with the Earth's magnetic field and six orders of magnitude smaller than the valence fluctuation scale. This tiny value of the upper bound on B_c, well inside the superconducting dome, raises the fascinating possibility that valence fluctuating beta-YbAlB4 is intrinsically quantum critical, without tuning the magnetic field, pressure, or composition: the first known example of such a phenomenon in a metal.

arXiv comment4 pages, 2 figures, proceedings for SCES 2011

References in corpus (8)

• Fermi-liquid instabilities at magnetic quantum phase transitions
• Quantum Criticality in Heavy Fermion Metals
• Fractionalized Fermi liquids
• Signatures of valence fluctuations in CeCu2Si2 under high pressure
• Quantum Criticality without Tuning in the Mixed Valence Compound beta-YbAlB4
• Kondo Breakdown and Hybridization Fluctuations in the Kondo-Heisenberg Lattice
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Cited by in corpus (4)

• Model for Ferromagnetic Quantum Critical Point in a 1D Kondo Lattice
• Topological basis for understanding the behavior of the heavy-fermion metal $\beta -\mathrm{YbAl}{\mathrm{B}}_4$ under application of magnetic field and pressure
• Field evolution of quantum critical and heavy Fermi-liquid components in the magnetization of the mixed valence compound beta-YbAlB4
• Strongly correlated Fermi systems as a new state of matter