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 β-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 |Bc| < 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 Bc, well inside the superconducting dome, raises the fascinating possibility that valence fluctuating β-YbAlB4 is intrinsically quantum critical, without tuning the magnetic field, pressure, or composition: the first known example of such a phenomenon in a metal.
|Original language||English (US)|
|Journal||Journal of Physics: Conference Series|
|State||Published - 2012|
|Event||International Conference on Strongly Correlated Electron Systems, SCES 2011 - Cambridge, United Kingdom|
Duration: Aug 29 2011 → Sep 3 2011
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)