Crystal growth and perfection of RENi2B2C (RE=Ho, Tb, Y)

Single crystals of HoNi2B2C, YNi2B2C and TbNi2B2C have been grown by a floating zone technique with optical heating. Crystals are crack free, show no traces of 2nd phases and are single crystalline in the whole volume with a neutron rocking curve half-width less than 0.45°. The superconducting properties of YNi2B2C crystals show the best characteristics reported up to now with superconducting transition widths of ΔTc= 0.1 K and residual resistivity ratios RRR up to 48. Single crystals of HoNi2B2C exhibit different types of superconducting properties: plain superconductivity, re-entrant superconducting behaviour and normal conductivity, which are triggered by a slight change of crystal stoichiometry and growth parameters.