Magnetic properties of the frustated fcc antiferromagnet HoB12 above and below TN

Abstract

We have investigated the magnetic ordering of the frustrated fcc antiferromagnet HoB12. Below TN 7.4K antiferromagnetic order and a complex phase diagram is observed. Above TN neutron scattering experiments show strong diffuse scattering. The diffuse signal indicates strong correlations between the rare earth moments along the [111] direction well above TN. The behavior of this component resembles low dimensional magnets which are known to show long range order only at T 0. Close to TN correlations perpendicular to the [111] direction get relevant, they diverge towards TN. Thus we observe a complex ordering process where the frustration is lifted in steps. The experimental data and their interpretation is presented, some of the possible microscopic origins are discusse