Abstract
We present a detailed study of magnetization in UCu2Ge2, a system that undergoes a ferromagnetic to antiferromagnetic transition as a function of temperature. The nature of the ferromagnetic and antiferromagnetic states involved, and also of the phase transition, do not seem to be conventional. Marked irreversibility is observed in the low-temperature antiferromagnetic state in an external field up to 2 T, and distinct irreversibility exists even for the ferromagnetic state in the low-field regime (H 7le; 50 mT).