Quantum criticality in Ce$_{1-x}$Sm$_x$CoIn$_5$

TL;DR

This study investigates how samarium substitution affects quantum criticality in CeCoIn$_5$, revealing a zero-field quantum critical point near x≈0.15 where antiferromagnetism and superconductivity coexist.

Contribution

It provides the first detailed analysis of the evolution of magnetic-field-induced quantum criticality with samarium doping in Ce$_{1-x}$Sm$_x$CoIn$_5$.

Findings

Quantum critical point decreases with increasing Sm concentration.

Zero-field QCP identified at x≈0.15 within coexistence region.

Scaling analysis confirms the existence of the QCP.

Abstract

Motivated by the possibility of observing the co-existence between magnetism and unconventional superconductivity in heavy-fermion Ce$_{1-x}$Sm$_x$CoIn$_5$ alloys, we studied how the samarium substitution on the cerium site affects the magnetic field-tuned-quantum criticality of stoicheometric CeCoIn$_5$ by performing specific heat and resistivity measurements. By applying an external magnetic field, we have observed Fermi-liquid to non-Fermi-liquid crossovers in the temperature dependence of the electronic specific heat normalized by temperature and of the resistivity. We obtained the magnetic-field-induced quantum critical point (QCP) by extrapolating to zero temperature the temperature - magnetic field dependence at which the crossovers take place. Furthermore, a scaling analysis of the electronic specific heat is used to confirm the existence of the QCP. We have found that the magnitude of the magnetic-field-induced QCP decreases with increasing samarium concentration. Our analysis of heat capacity and resistivity data reveals a zero-field QCP for $x_\textrm{cr} \approx 0.15$, which falls inside the region where Sm ions antiferromagnetism and superconductivity co-exist.