THE MAGNETIC PHASES OF NDCU2

The magnetic phase diagram of a NdCu2 single crystal is investigated b y means of specific-heat measurements and neutron diffraction as a fun ction of temperature and external magnetic field applied along the cry stallographic b-direction. In the low temperature region we observe th ree commensurate phases AF1, F1, and F2. Their magnetic structures all consist of ferromagnetic (bc)-planes with different stacking sequence s along the a-direction comprising 5, 3 and 8 chemical unit cells, res pectively. Above 2.8 T the system is in a ferromagnetically aligned st ate (F3). Furthermore, there is an incommensurate phase AF3 between th e low temperature commensurate phases and the paramagnetic state and, in a very narrow temperature region of only 0.2 K, an intermediate pha se AF2 between AF1 and AF3. The Nd-moments are oriented along the b-di rection in all phases.