(Lu1-xYbx)Ni2B2C: From 16 K superconductor to heavy fermion

YbNi2B2C has recently been discovered to be a heavy fermion with a low-temperature Sommerfeld coefficient of 530 mJ/molK(2) and no magnetic order above 0.35 K. Based on thermodynamic and transport measurements on single-crystal samples the Kondo temperature is T-K approximate to 10 K. As a member of the RNi2B2C (R = Dy-Lu) series of magnetic superconductors R = Yb is remarkable since it does not superconduct for T > 0.35 K, even though the T-C's for TmNi2B2C and LuNi2B2C are 10.8 and 16.3 K, respectively. This is further evidence of the strong hybridization between the Yb 4f-levels and the conduction electrons. Electrical resistivity and specific heat data on single-crystal samples of (Yb1-xLux)Ni2B2C demonstrate how there is a systematic progression from a relatively high-temperature superconductor to a heavy fermion.