Neutron diffraction studies of canted antiferromagnetic ordering in Co II hydroxide terephtalate

The ordered magnetic structure of fully deuterated Co II hydroxy terephthalate Co2 OD 2 tp d4 tp d4 C8D4O4 1 has been determined at various temperatures by neutron powder diffraction analysis. The layered nuclear structure is in agreement with that found from X Ray powder diffraction data and the hydrogen atoms D were located in the crystallographic cell. Below the ordering temperature, TC 48 K, the magnetic diffraction patterns reveal the existence of different magnetic moments on two non equivalent Co II ions forming ferrimagnetic layers. Zero field cooled experiments show that the long range magnetic order is basically antiferromagnetic along the stacking axis, with possible weak canting within the layers. In field cooled experiments, strongly canted antiferromagnetism is observed with a resulting ferromagnetic component of 1.8 muB along the b axis on one of the Co sites. It is shown that this phase is metastable, the weakly canted phase being the ground state at very low temperatur