Abstract
We have, for the first time, succeeded in preparing a single crystal of UNi2Al3 exhibiting both superconducting and antiferromagnetic ordered phase transitions. The magnetic susceptibility in the normal and paramagnetic state for the external magnetic field H applied parallel to the hexagonal a-axis, is found to be larger than that for the field applied along the c-axis. The upper critical magnetic field Hc2(T) for H // a-axis is much larger than that for H // c-axis. No flattening due to the Pauli limiting effect has been observed in the Hc2 vs. T curve. Comparison of these results with those of the isostructural compound UPd2Al3 suggests that the superconducting state is strongly related to the antiferromagnetic ordered state.
