Electron tunneling into superconductingCeRu2

The superconducting energy gap of CeRu{sub 2} has been studied by break-junction tunneling. The observed gap values 2{Delta}(0)=1.9{endash}2.6 meV with T{sub c}=5.4{endash}6.7 K give the ratio 2{Delta}(0)/k{sub B}T{sub c}=4.1{endash}4.4, indicating a strong-coupling superconductor. The temperature dependence of the gap value is in good agreement with the BCS prediction. {copyright} {ital 1997} {ital The American Physical Society}