Influence of Nd magnetic subsystem on spin-reorientation phase transition in Nd2CuO4 at low temperature

Acoustic measurements on Nd2CuO4 single crystals have recently revealed a ferroelastic phase transition at about T-c = 5 K. In view of the strong magnetoelastic coupling in the compound it was attributed to an additional reorientation of Cu spins. In the present report it is shown that this transition can be successfully described if one takes the Nd magnetic subsystem into account explicitly. This approach requires treating a phenomenological Hamiltonian within invariants of the fourth order in spins only, which is natural for a tetragonal symmetry of the system. Complementary information about the strength of Nd-Nd interactions has been derived. (C) 1997 American Institute of Physics.