Magnetic Phase Transition and Magnetization Plateau in Cs 2 Cubr 4

The crystal structure of Cs2CuBr4 is the same as that of Cs2CuCl4, which has been characterized as a spin1 2 quasi-two-dimensional frustrated system. The magnetic properties of Cs2CuBr4 were investigated by magnetization and specific heat measurements. The phase transition at zero magnetic field was detected at TN = 1.4 K. It was observed that the magnetization curve has a plateau at about one-third of the saturation magnetization for magnetic field H parallel to the band c-axes, while no plateau was observed for H ‖ a. The field-induced phase transition to the plateau state appears to be of the first order. The mechanism leading to the magnetization plateau is discussed.