Local spin susceptibility of the S=12 kagome lattice in ZnCu3(OD)6Cl2

We report a single-crystal D2 NMR investigation of the nearly ideal spin S=1/2 kagome lattice ZnCu3(OD)6Cl2. We successfully identify D2 NMR signals originating from the nearest neighbors of Cu2+ defects occupying Zn sites. From the D2 Knight-shift measurements, we demonstrate that weakly interacting Cu2+ spins at these defects cause the large Curie-Weiss enhancement toward T=0 commonly observed in the bulk susceptibility data. We estimate the intrinsic spin susceptibility of the kagome planes by subtracting defect contributions, and explore several scenarios.