Magnetism and high-field magnetization of RCu2

We measured the magnetization of CeCu2, PrCu2, TbCu2, DyCu2 and TmCu2 in high magnetic fields up to 40T and in a wide temperature range from 1.3 to 150K, and observed a metamagnetic transition with a large hysteresis. The present metamagnetic transition occurs in the ac-plane of the orthorhombic crystal structure, which was analysed on the basis of the quadrupole moment O22.