Quantum criticality and superconducting pairing in Ce1-xYbxCoIn5 alloys

Charge transport measurements under magnetic field and pressure on Ce1-xYbxCoIn5 single crystalline alloys revealed that: (i) relatively small Yb substitution suppresses the field induced quantum critical point, with a complete suppression for Yb doping x > 0.07; (ii) the superconducting transition temperature (Tc) and Kondo lattice coherence temperature (Tcoh) decrease with x, yet they remain finite over the wide range of Yb concentrations; (iii) both Tc and Tcoh 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 the pressure dependence of both Tcoh and Tc within the composite pairing theory. In the purely static limit, we find that the composite pairing mechanism necessarily causes opposite behaviors of Tcoh and Tc with pressure: if Tcoh grows with pressure, Tc must decrease with pressure and vice versa.