TRANSPORT AND MAGNETIC MEASUREMENTS ON SINGLE-CRYSTAL RARE EARTH-NICKEL-BOROCARBIDES

RNi(2)B(2)C (R=Y, Lu-Gd) intermetallics show diverse behavior, includi ng moderately high temperature superconductivity (R=Y, Lu), coexistenc e of superconductivity with magnetic order (R=Tm-Dy), only magnetic or der (R=Tb, Gd), and heavy fermion behavior without superconductivity o r magnetic order (R=Yb). The large energy scale of the crystal electri c field splitting of lanthanide orbitals leads to large anisotropies i n the magnetic and superconducting properties of many of these compoun ds. Single crystal transport measurements can help determine the influ ence of anisotropy on magnetic and superconducting phase boundaries as illustrated by the phase diagram for HoNi2B2C determined by transport and magnetic measurements and delineate the important scattering mech anisms by resistivity and thermopower measurements across the series.