Theory for Non-Fermi Liquid Temperature Dependence in Resistivity of Ce_xLa_{1-x} Cu_{5.62} Au_{0.38} (x=0.02-0.10) on the Local Quantum Valence Criticality of Ce Impurities

Abstract

It was reported by Shiino et al in J. Phys. Soc. Jpn. 86, 123705 (2017) that Ce_xLa_{1-x} Cu_{5.62} Au_{0.38} (x=0.02-0.10) exhibits a new type of quantum criticality in both magnetic and thermal properties, which is the same as that observed in a series of materials exhibiting quantum critical valence fluctuations (QCVF), such as \beta-YbAlB_4, Yb_{15}Al_{34}Au_{51}, and so on. However, the temperature (T) dependence in the resistivity rho(T) for T<0.5K is quite anomalous, i.e., \rho(T)\propto (const.-T^{n}) with n \simeq 0.75 at x=0.05. We find that this anomalous exponent is given by n=2(1-\zeta), with zeta being the weakly temperature dependent (0.5 \lsim \zeta \lsim 0.7) critical exponent for the QCVF.The observed critical exponent n\simeq 0.75 at x=0.05 is reproduced by choosing \zeta\simeq 0.63 which is consistent with the divergent behavior observed in the uniform magnetic susceptibility \chi\propto T^{-\zeta} with \zeta\simeq 0.67 at x=0.02.