Magnetic frustration and order in gadolinium gallium garnet

In gadolinium gallium garnet (GGG) there is no long-range magnetic order do wn to 25 mK even though the Curie-Weiss temperature is - 2 K. Instead, over a wide temperature range GGG supports short-range magnetic order (spin liq uid), while long-range order can be induced by an applied magnetic held. It is believed that the geometrical frustration of the magnetic interactions is responsible for this behaviour: in GGG the magnetic Gd ions are located on a triangular lattice. We have investigated the magnetic properties of GG G by neutron diffraction measurements. The results show clearly the develop ment of short-range magnetic order without an applied field and the appeara nce of long range order in an applied magnetic held. A comparison of the ex perimental data with classical Monte Carlo simulations results provides us with hrm conclusions about the relative strength of the magnetic interactio ns in GGG and their importance in the formation of a magnetic ground state. (C) 1999 Elsevier Science B.V. All rights reserved.