Anisotropic Magnetism of the Shastry-Sutherland Lattice Material BaNd2PtO5

Single crystals were grown and characterized to investigate the physical properties and magnetic ground state of BaNd2PtO5, a candidate to host physics of the Shastry-Sutherland model. Analysis of single crystal x-ray diffraction data yields an updated crystal structure, similar to the prior report but now in space group P4/mbm. Magnetization and specific heat measurements reveal an antiferromagnetic transition at TN = 1.9 K and a large magnetic anisotropy with in-plane magnetization much larger than out-of-plane magnetization. Single crystal neutron diffraction at zero field reveals a propagation vector of (1/2 1/ 2 1/2) for the magnetic ground state as compared to the (1/2 1/2 0) wave vector observed in the related body-centered material BaNd2ZnO5. The ground state is found to be a fully compensated antiferromagnet with diffraction data well fitted within the magnetic space group P-S-1 (BNS setting #2.7). The ordered moment is mostly in the basal plane with nearest neighbors forming ferromagnetic dimers, however it also has a finite out-of-plane component unlike the related easy-plane materials BaNd2ZnO5 and BaNd2ZnS5. Field-induced transitions are observed below TN when the field is applied within the basal plane, and in-plane anisotropy of the associated critical fields is observed. The magnetization is strongly impacted by misalignment of the field away from high symmetry directions. These results suggest complex magnetic structures may arise in the field-induced states, and they highlight the need for extreme care when studying this and related Shastry-Sutherland materials.