Neutron diffraction study of magnetic structures in single crystal Ho ₂PdSi₃ in magnetic fields up to 5 T

Due to the interplay between RKKY exchange interaction, crystalline-electric field (CEF) effects and geometric frustration due to the AlB₂-derived hexagonal crystal structure, the study of R ₂PdSi₃ (R = rare earth) has been found to be a challenging field in rare earth magnetism. In this contribution we present the results of neutron diffraction experiments on a Ho₂PdSi₃ single crystal in the magnetically ordered state at T = ≤ 1.6 K. The compound orders antiferromagnetically in the basal plane with the propagation vector τ = (1/7-δ, 2δ, 0) where δ ∼ 0.01 r.l.u. In magnetic fields applied along the (11̄0) magnetic hard axis, the structure persists up to the highest measured field of 5 T. The dependence of the intensities as a function of field suggests that the τ structure is a single-k multi-domain structure.