Non-conventional superconductivity in the strong-coupling limit for the heavy fermion system CeCoIn5

Y. FASANO; P. SZABO; J. KACMARCIK; Z. PRIBULOVA; P. PEDRAZZINI; P. SAMUELY; V.CORREA; N. HABERKORN

Buenos Aires

Conferencia; Contributed Talk in the Superconductivity session of LT27 (27th International Conference in Low Temperatures); 2014

Heavy-fermion systems such as   CeCoIn5 are interesting candidates to study the microscopic coupling giving rise to unconventional superconductivity in concomitance with magnetic order. Scanning tunneling microscopy is a suitable technique to study this issue since measuring the tunnel conductance provides information on the local density of states of the system. We present data on the temperature-evolution of the quasiparticle excitation spectrum of  CeCoIn5 between 300 mK and 3K (Tc = 2.2 K). For temperatures  T< Tc the spectral weight can be reasonably fitted considering a d-wave symmetry for the superconducting gap D. The obtained ratio 2D/kTc ~6 indicates CeCoIn is a non-conventional superconductor in the strong limit, finding also supported by specific heat measurements. In striking parallel with cuprate superconductors,  the tunneling conductance shows a depletion at energies smaller than D for temperatures larger than Tc, suggesting the existence of a pseudogap phase up to 1.25Tc.