Spin rotation in ErGa3

The magnetic phase diagram of ErGa3, built up from bulk magnetisation data, shows in zero-applied magnetic field two successive transitions at T-1 = 2 .6 and T-2 congruent to 2.5 K, respectively. The magnetic ordering of ErGa3 examined by neutron diffraction, can be derived from the so-called {1/2, 1 /2, 0} structure, i.e. one in which the successive antiparallel(1 1 0) shee ts of spins have additionally superimposed on them a sinusoidal modulation parallel to the [1 0 0] axis. The temperature dependence of neutron diffrac tion diagrams studied on the single crystal, revealed in the range of (2.6- 2.78) K an abrupt reorientation of the Er3+ spins from the nearly [1 1 0] d irection, towards the [1 0 0] axis. In this way previously observed effect on the polycrystalline sample has been confirmed. This rotation can be attr ibuted to the T-1 transition found in the H-T magnetic phase diagram. (C) 2 000 Elsevier Science B.V. All rights reserved.