High-Field Magnetization and ESR Studies of Two-Dimensional Triangular-Lattice Antiferromagnet Cu2(OH)3Cl

We report the high-field magnetization and electron spin resonance (ESR) for the two-dimensional triangular-lattice antiferromagnet Cu-2(OH)(3)Cl. The compound has an antiferromagnetic (AFM) order at T-N = 6.8 K and undergoes a field-induced metamagnetic transition at 3 T. The high-field magnetization up to 50 T shows a half-saturated ferromagnetic (FM)-like magnetization behavior, suggesting that the Cu1 FM chain and the Cu2 AFM chain are decoupled in magnetism. The temperature-dependent ESR spectra follow the development of magnetic correlations and AFM ordering. Corresponding to the magnetic decoupling, the observed ESR modes originate only from the Cu1 spins. The magnetic anisotropy fields are estimated as H-A1 = 4.33 T and H-A2 = 6.66 T, which are larger than those in Cu-2(OH)(3)Br. The intrachain and interchain exchanges are estimated to be 20 K and - 4.2 K, respectively, for the Cu1 spins.