Magnetic phase transitions and structures of Co3V 2O8

Co3V 2O8 is a spin- 3/2 system on a Kagomé staircase and is known to undergo two magnetic phase transitions between 6 and 11 K. The H – T phase diagram of Co3V 2O8 derived by magnetization measurements on a single crystal is presented. Additionally both ordered magnetic structures were investigated by neutron powder diffraction experiments and solved using Bertaut’s macroscopic theory. For the ferromagnetic phase the magnetic moments of the Co2+ ions were found to be 1.5 ( 3 ) μ B and 2.7 ( 1 ) μ B at 3.5 K along the crystallographic a axis for the (4a) and (8e) sites, respectively. The antiferromagnetic phase exhibits a magnetic cell with a doubled b axis with respect to the nuclear one. The magnetic moments point along the a axis being 1.8 ( 2 ) μ B (4a) and 1.8 ( 1 ) μ B (8e) at 8 K.