Structure and 3/7-like Magnetization Plateau of Layered Y2Cu7(TeO3)6Cl6(OH)2 Containing Diamond Chains and Trimers.

We have synthesized a new spin-1/2 antiferromagnet, Y2Cu7(TeO3)6Cl6(OH)2, via a traditional hydrothermal method. This compound crystallizes in the triclinic crystal system with space group P1̅. The magnetic ions constitute a two-dimensional layered lattice with a novel topological structure in which the Cu4 clusters make up distorted diamond chains along the a axis and these chains are connected by the Cu3 trimers. The magnetic susceptibility and specific heat measurements show that the compound is antiferromagnetically ordered at TN = 4.1 K. This antiferromagnetic ordering is further supported by electron spin resonance (ESR) data. The magnetization curve presents a field-induced metamagnetic transition at 0.2 T, followed by a magnetization plateau within a wide magnetic field range from 7 T to at least 55 T, which corresponds to 3/7 of the saturated magnetization with g = 2.15 obtained from ESR. The possible mechanism for the magnetization plateau is discussed.