Doping And Pressure Studies On Ybbipt

The compound YbBiPt exhibits an extremely large low-temperature C/T (gamma approximately 8 J K-2 mol-1/Yb) which, if due solely to a renormalized effective mass, would make this material the heaviest correlated electron system known to date. In the Kondo model, the very large gamma corresponds to a small characteristic energy scale that is expected to be pressure dependent. We have studied the effect of chemical pressure on YbBiPt single crystals by heat-capacity measurements on Y and Lu-doped samples. We have also made preliminary low-temperature measurements under hydrostatic pressure of the heat capacity (300 mK < T < 2 K, up to 8 kbar) and resistance (30 mK < T < 1 K, at 16 kbar).