31P NMR studies of the 13-depleted two-dimensional anisotropic kagome lattice system BaCu2(PO4)2(H2O)

The subtle interaction of low dimensionality and spin correlations in two-dimensional quantum magnets results in novel states of matter. Herein, we investigate the structural, magnetic, heat capacity, 31P nuclear magnetic resonance (NMR) measurements, and density functional theory + Hubbard U (DFT +U) electronic structure calculations on the Cu2+(S = 12)-based compound BaCu2(PO4)2(H2O). Based on the hopping parameters obtained from DFT, the titled compound comprises the 2D layer of 1/3-depleted anisotropic kagome lattice with the magnetic couplings J1, J2, J3, and J4. At high temperatures, magnetic susceptibility (chi) exhibits paramagnetic behavior, with a Curie-Weiss temperature of theta CW approximate to -67 K, indicating the presence of dominant antiferromagnetic interactions. The appearance of a broad maximum in the magnetic susceptibility and heat capacity reveals the low-dimensional nature of the compound. While the sharp magnetic anomaly features are not seen clearly in the bulk measurements, the 31P NMR local probe measurements unambiguously show the presence of magnetic transition at TN = 10.5 K. The temperature (T) dependence of nuclear spin-lattice relaxation rate (1/T1) exhibits a sharp peak at TN. While 1/T1 falls very steeply below TN, it follows a sublinear power-law behavior above TN, indicating the presence of dynamic short-range correlations, which could be attributed to the complex 2D spin network of the compound.