Magnetic frustration and order in gadolinium gallium garnet

Abstract

In gadolinium gallium garnet (GGG) there is no long-range magnetic order down 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 liquid), while long-range order can be induced by an applied magnetic field. 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 GGG by neutron diffraction measurements. The results show clearly the development of short-range magnetic order without an applied field and the appearance of long range order in an applied magnetic field. A comparison of the experimental data with classical Monte Carlo simulations results provides us with firm conclusions about the relative strength of the magnetic interactions in GGG and their importance in the formation of a magnetic ground state.