We report the magnetic properties of single crystals of Na_(x)CoO_(2) (x(velence)0.42, 0.82, and 0.87). The magnetic susceptibility measurements revealed considerable anisotropy along Hab and Hc for the as-grown single crystals. It was found that an antiferromagnetic transition with a Neel temperature T_(N)velence21 K occurred for the x(velence)0.82 sample, and there was a paramagnetic phase for the x(velence)0.87 sample over a wide temperature range from 2 to 300 K, but the sample with x(velence)0.42 shows a monotonic increase of X with increasing temperature above approx100 K. In addition, the x(velence)0.82 sample has the largest derived anisotropic g-factor ratio (g_(ab)/g_(c) approx 1.30), whereas the sample with x(velence)0.42 is nearly isotropic (g_(ab)/g_(c)approx0.96).
展开▼
