The magnetic properties of Gd2CuO4 have been investigated by magnetiza
tion, electron paramagnetic resonance (EPR) and neutron-diffraction me
asurements in the temperature range 1.5-50 K to determine the magnetic
phase diagram and to search for the origin of the weak ferromagnetism
which has been observed in this compound. Gd2CuO4 is found to have a
rather complex magnetic phase diagram consisting of at least four dist
inct magnetic phases. The nature of the weak ferromagnetism is discuss
ed and a possible origin of both the weak ferromagnetism and the phase
transitions is proposed.