Peculiarities of magnetic ordering in the S=5/2 two-dimensional square-lattice antimonate NaMnSbO4

An orthorhombic compound, $\mathrm{NaMnSb}{\mathrm{O}}₄$, represents a square net of magnetic $\mathrm{M}{\mathrm{n}}²⁺$ ions residing in vertex-shared oxygen octahedra. Its static and dynamic magnetic properties were studied using magnetic susceptibility, specific heat, magnetization, electron spin resonance (ESR), nuclear magnetic resonance (NMR), and density-functional calculations. Thermodynamic data indicate an establishment of the long-range magnetic order with ${T}_{\mathrm{N}}\ensuremath{\sim}44\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, which is preceded by a short-range one at about 55 K. In addition, a nontrivial wasp-waisted hysteresis loop of the magnetization was observed, indicating that the ground state is most probably canted antiferromagnetic. Temperature dependence of the magnetic susceptibility is described reasonably well in the framework of two-dimensional square-lattice model with the main exchange parameter $J=\ensuremath{-}5.3\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, which is in good agreement with density-functional analysis, NMR, and ESR data.