Observation of weak ferromagnetism and the sizable magnetocaloric effect in Co2V2O7

The magnetic behavior of cobalt pyrovanadate compound Co2V2O7 with dichromate structure is reported. The compound undergoes long range magnetic ordering below TC=8 K and our study identifies the ground state to be a canted antiferromagnetic type with a weak ferromagnetic component. The transition at TC is found to be first-order in nature as evident from the presence of distinct thermal hysteresis in the temperature dependent magnetization data. Below TC, a significantly large value of magnetic relaxation is observed which is possibly due to the metastability associated with the first order phase transition. Interestingly, the sample exhibits a sizable magneto-caloric effect around TC (∼4.1 J kg−1. K−1 for 50 kOe of field change) which is reasonably high among antiferromagnetic transition metal oxides with weak ferromagnetism.