Effect of Disorder Induced by Heavy-Ion Irradiation on CeCoIn5 Superconductivity

We present a study of the effect of heavy-ion irradiation on a thinned single crystal of the unconventional heavy fermion superconductor CeCoIn5. Magnetic susceptibility and low-temperature specific heat results show that the superconducting transition temperature (Tc) changed only 4% with irradiation of 1×1012 ions/cm2, Energy=1 GeV, while the specific heat jump at Tc, ΔC, divided by Cn, where Cn is the normal state specific heat just above Tc, was reduced to 3.6 from ΔC/Cn=4.5 for unirradiated CeCoIn5. The increase of low-temperature magnetic susceptibility and the saturation in magnetization suggest that the defects induced by heavy-ion irradiation are magnetic in nature, as was seen in the case of neutron irradiation on the heavy fermion superconductors, UBe13 and UPt3. The non-Fermi liquid behavior of the irradiated sample, based on the temperature dependence of the low temperature magnetic susceptibility, is significantly altered.