Magnetic properties of the nearly two-dimensional ferromagnets [C6H5(CH2)nNH3]2CuCl4 with n=1,2,3

Magnetic susceptibility and nuclear magnetic resonance of Cu and Cl nuclei have been studied in monocrystals of [C6H5(CH2)nNH3]2CuCl4 with n=1,2,3 below 4.2 K. These compounds are two-dimensional ferromagnets with a dominant XY-type anisotropy. For the compound with n=1, the Ising anisotropy is extremely small. The NMR measurements of the temperature and field dependence of the magnetization are consistent with a two-dimensional spin-wave model and allowed us to determine the value of the intralayer exchange integral.