Magnetization isotherms on ErNi2B2C, Er0.8Tb0.2Ni2B2C and Er0.8Lu0.2Ni2B2C single crystals

Abstract The magnetic and superconducting properties of ErNi 2 B 2 C, Er 0.8 Tb 0.2 Ni 2 B 2 C and Er 0.8 Lu 0.2 Ni 2 B 2 C single crystals have been studied by DC magnetization measurements. Those crystals were grown by a floating zone method. The superconducting transitions ( T C ) were observed at 8.9, 4.0 and 11.1 K in ErNi 2 B 2 C, Er 0.8 Tb 0.2 Ni 2 B 2 C and Er 0.8 Lu 0.2 Ni 2 B 2 C, respectively. The field dependence of magnetization in ErNi 2 B 2 C showed a drastic change from negative to positive just over H C1 (400 Oe) in increasing applied field at 1.8 K near the weak ferromagnetic transition. A double meta-magnetic transition at 11 and 19 kOe was also observed. Although the opposite effects on ErNi 2 B 2 C doped with magnetic Tb and non-magnetic Lu were expected, all such anomalies were absent in Er 0.8 Tb 0.2 Ni 2 B 2 C and Er 0.8 Lu 0.2 Ni 2 B 2 C.