Neutron scattering on HoB₁₂ - short-range correlations above T_{N}

Neutron scattering experiments on frustrated fcc - antiferromagnet HoB$_{12}$ have been performed above T$_{N}$ = 7.4 K. Diffuse scattering patterns indicate that above Neel temperature correlations between neighboring magnetic moments of Ho - ions appear, similar to the appearance of coupled spin-pairs (dimers) in low dimensional magnets. Moreover, the diffuse patterns show a symmetry reduction from fcc to simple cubic. Analogous behavior in 3D systems is not known, although it was predicted by theory. The role of various interactions leading to this behavior is being analyzed and discussed.