Magnetic properties of isostructural spin-ladder systems (C5H12N)2CuCl4 and (C5H12N)2CuCl2Br2

We synthesized two compounds, (C 5 H 12 N) 2 CuCl 4 (hereafter BPCC) and (C 5 H 12 N) 2 CuCl 2 Br 2 (hereafter BPCCB), and have performed the crystal-structure analysis, and susceptibility, magnetization and ESR measurements. The experimental results of BPCC are in good agreement with a two-leg ladder model with a strong-dimer-coupling limit. However, the compound, BPCCB, is close to a ladder model with isotropic coupling limit.