Magnetization and ac susceptibility in the vortex state of κ-(BEDT-TTF)2Cu[N(CN)2]Br

The vortex state in κ-(BEDT-TTF)2Cu[N(CN)2]Br is studied by transport and magnetization measurements. The so-called second peak, which is considered as a manifestation of dimensional crossover in the vortex system, appeared in the M-H curve. The overall phase diagram obtained in the present study was similar to the reported phase diagram of κ-(BEDT-TTF)2Cu(NCS)2. In addition, an anomalous cooling rate dependence of M-H curve was observed.