title: Structure and magnetism of S = 1/2 kagome antiferromagnets NiCu3(OH)6Cl2 and CoCu3(OH)6Cl2.
abstract: We have successfully synthesized S = 1/2 kagome antiferromagnets MCu(3)(OH)(6)Cl(2) (M = Ni and Co) by a hydrothermal method with a rotating pressure vessel. Structural characterization shows that both compounds have similar crystal structure to ZnCu(3)(OH)(6)Cl(2) with R3m symmetry. As with ZnCu(3)(OH)(6)Cl(2), the compounds show no obvious hysteresis at 2 K. A spin-glass transition is found in both NiCu(3)(OH)(6)Cl(2) and CoCu(3)(OH)(6)Cl(2) at low temperatures (6.0 and 3.5 K respectively) by AC susceptibility measurements. This indicates no long-range magnetic order and a strong spin frustration. The substitution of Zn(2+) by magnetic ions Ni(2+) or Co(2+) effectively enhances the interlayer exchange coupling and changes the ground state of the kagome spin system.
authors.affiliation: Department of Physics, Renmin University of China, Beijing, People's Republic of China.
authors.forename: Yue-sheng
authors.initials: YS
authors.lastname: Li
authors.forename: Qing-ming
authors.initials: QM
authors.lastname: Zhang
mesh_terms: D003198:Computer Simulation; D059346:Magnets; D008422:Materials Testing; D008670:Metals / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular
chemical_list: D008670:Metals