MAGNETIC PHASE-DIAGRAM IN NDIN3 ANTIFERROMAGNET

The NdIn3 compound, which crystallizes in the AuCu3-type cubic structu re, orders antiferromagnetically at T(N) = 5.9 K. In zero-field it und ergoes two successive first-order magnetic transitions at T1 = 5.2 K a nd T2 = 4.7 K. Just below T(N), the magnetic structure is sine modulat ed, q over arrow pointing right = (1/2,1/2,0.036), at T1 the structure squares up with a propagation vector q over arrow pointing right = (1 /2,1/2,0.017), before to stabilize into the commensurate q over arrow pointing right = (1/2,1/2,0) below T2. In these three single-q over ar row pointing right phases, the magnetic moments remain aligned along t he fourfold axis. We present here an extensive study in the whole anti ferromagnetic range, by magnetization measurements in fields up to 14 T and by neutron diffraction up to 10 T. Along the three high symmetry axes of the crystallographic structure, the magnetization presents nu merous metamagnetic transitions. The corresponding (H-T) magnetic phas e diagrams have been determined. In particular, the [001] phase diagra m reveals the existence at low temperatures of two high-field induced magnetic phases. Surprisingly, in these phases, the most probable magn etic arrangements arc multi-q over arrow pointing right structures, wi th q over arrow pointing right belonging to the [1/2,1/2,0] crystallog raphic star. As for the low-temperature commensurate structure, the ma gnetic moments keep pointing along the fourfold axes and the field-ind uced transitions arc explained by the successive flips of two moments towards the direction of the field.