Pronounced non‐Fermi‐liquid behavior of the quantum critical heavy fermion superconductor β‐YbAlB4

Abstract

AbstractQuantum criticality has been a central subject in the study of heavy fermion systems, partly because of the emergence of non‐trivial collective phenomena near criticality such as unconventional superconductivity and non‐Fermi‐liquid behavior. While a number of heavy fermion systems have been studied in Ce(4f1) based compounds, examples of quantum critical materials are still scarce in their hole analogs, namely Yb(4f13) based heavy fermion systems. Here we review the low temperature transport and thermodynamic properties hitherto found for the Yb based heavy fermion superconductor β‐YbAlB4 $(T_{\rm c} = 80\,{\rm mK})$. The observations indicate that it provides a rare example of a pure metal that displays quantum critical behavior at ambient pressure and under zero applied magnetic field.