Quantum criticality and superconducting pairing in Ce(1-x)Yb(x)CoIn5 alloys

TL;DR

This paper reviews experimental and theoretical studies on Ce(1-x)Yb(x)CoIn5 alloys, focusing on quantum criticality, superconductivity, and the effects of Yb substitution and pressure on their properties.

Contribution

It provides new insights into how Yb doping and pressure influence quantum critical points, superconducting temperature, and quasiparticle contributions in heavy-fermion alloys.

Findings

Yb substitution suppresses the quantum critical point.

Superconducting and coherence temperatures decrease with Yb doping but remain finite.

Pressure increases both superconducting and coherence temperatures.

Abstract

In this paper we review some of our recent experimental and theoretical results on transport and thermodynamic properties of heavy-fermion alloys Ce(1-x)Yb(x)CoIn5. Charge transport measurements under magnetic field and pressure on these single crystalline alloys revealed that: (i) relatively small Yb substitution suppresses the field induced quantum critical point, with a complete suppression for nominal Yb doping x>0.20; (ii) the superconducting transition temperature Tc and Kondo lattice coherence temperature T* decrease with x, yet they remain finite over the wide range of Yb concentrations; (iii) both Tc and T* increase with pressure; (iv) there are two contributions to resistivity, which show different temperature and pressure dependences, implying that both heavy and light quasiparticles contribute to inelastic scattering. We also analyzed theoretically the pressure dependence of both T* and Tc within the composite pairing theory. In the purely static limit, when we ignore the lattice dynamics, we find that the composite pairing mechanism necessarily causes opposite behaviors of T* and Tc with pressure: if T* grows with pressure, Tc must decrease with pressure and vice versa.