Zero-Field Quantum Critical Point in Ce$_{0.91}$Yb$_{0.09}$CoIn$_5$

TL;DR

This study identifies a zero-field quantum critical point in Ce$_{0.91}$Yb$_{0.09}$CoIn$_5$, revealing non-Fermi liquid behavior, a third-order phase transition at 7 K, and an antiferromagnetic quantum phase transition without external magnetic field influence.

Contribution

It provides experimental evidence of a zero-field quantum critical point in a heavy-fermion superconductor through scaling analysis and thermodynamic measurements, highlighting its antiferromagnetic nature.

Findings

Observation of non-Fermi liquid to Fermi liquid crossover.

Identification of a zero-field quantum critical point.

Detection of a third-order phase transition at 7 K.

Abstract

We present results of specific heat, electrical resistance, and magnetoresistivity measurements on single crystals of the heavy-fermion superconducting alloy Ce$_{0.91}$Yb$_{0.09}$CoIn$_5$. Non-Fermi liquid to Fermi liquid crossovers are clearly observed in the temperature dependence of the Sommerfeld coefficient $\gamma$ and resistivity data. Furthermore, we show that the Yb-doped sample with $x=0.09$ exhibits universality due to an underlying quantum phase transition without an applied magnetic field by utilizing the scaling analysis of $\gamma$. Fitting of the heat capacity and resistivity data based on existing theoretical models indicates that the zero-field quantum critical point is of antiferromagnetic origin. Finally, we found that at zero magnetic field the system undergoes a third-order phase transition at the temperature $T_{c3}\approx 7$ K.