Single crystal synthesis and anisotropic magnetization of TMSb2O4 (TM = Mn, Co, Ni)

The synthesis, single crystal growth and anisotropic magnetization study of high-quality, single crystals in the TMSb₂O₄ (TM = Mn, Co, Ni) series are reported. Columnar crystals, several millimeters in length, crystallized in the tetragonal space group, P4₂/mbc, were obtained by a high-temperature hydrothermal method. Magnetization studies of crystals aligned in an external magnetic field respective to the principal crystallographic axes were performed and allowed study of the 1D intrachain interactions of octahedral TM²⁺ edge-shared chains along the c-axis, as well as the wider 3D magnetic superstructure arising from through-space interchain interactions. Magnetic susceptibility measurements revealed strong ordering behavior when fields were applied along the chains that were contrasted by a more muted response for chain orientations normal to the applied field. The field- and cooling-dependent ordering transitions found in the CoSb₂O₄ system when a field is applied perpendicular to the S = 3/2 Co²⁺ chains is complex and highlights the highly anisotropic spin exchange coupling between the intrachain, nearest-neighbor (NN), and next-nearest-neighbor (NNN) interactions. Specific heat measurements revealed a field-dependent secondary ordering feature at 13.5 K that, on application of 90 kOe applied fields, is suppressed and broadened, which matches behavior seen in the field-dependent susceptibility. The anisotropic magnetic coupling provides a roadmap for additional study of single crystals of other 1D chains.