Anisotropic magnetic properties of antiferromagnetic DyCoGa5

We report a detailed study of the physical properties of single crystals of DyCoGa₅ using magnetic susceptibility, specific heat, and resistivity measurements. DyCoGa₅ crystallizes in the layered tetragonal HoCoGa₅-type structure and undergoes two successive antiferromagnetic transitions at TN1 = 24.7 K and TN2=22.9 K, which are associated with ordering of the Dy³⁺ moments. We characterize the temperature-field phase diagrams of DyCoGa₅ for fields both along the c axis and within the $ab$ plane, where highly anisotropic magnetic behaviors are observed. When fields are applied along the easy c axis, both TN1 and TN2 are suppressed with increasing field, and multiple metamagnetic transitions are observed, while these transitions exhibit only a weak field dependence for H∥ab. From our analysis we propose a crystalline-electric-field scheme that gives rise to the observed Ising anisotropy, and a simple model of the magnetic exchange interactions can account for the low-temperature antiferromagnetic phase, as well as the field-induced phase with a magnetization half the saturated value.