Magnetic and magnetocaloric properties of quasi-one-dimensional Ising spin chain CoV2O6.

We have investigated the magnetic and magnetocaloric properties of antiferromagnetic Ising spin chain CoV₂O₆ by magnetization and heat capacity measurements. Both monoclinic α-CoV₂O₆ and triclinic γ-CoV₂O₆ exhibit field-induced metamagnetic transitions from antiferromagnetic to ferromagnetic state via an intermediate ferrimagnetic state with 1/3 magnetization plateau. Due to the field-induced metamagnetic transitions, these systems show large conventional as well as inverse magnetocaloric effects. In α-CoV₂O₆, we observe field-induced complex magnetic phases and multiple magnetization plateaus below 6K when the field is applied along c axis. Several critical temperatures and fields have been identified from the temperature and field dependence of magnetization, magnetic entropy change, and heat capacity to construct the H-T phase diagram. As compared to α-CoV₂O₆, γ-CoV₂O₆ displays a relatively simple magnetic phase diagram. Due to the large magnetic entropy change and adiabatic temperature change at low or moderate applied magnetic field, γ-CoV₂O₆ may be considered as a magnetic refrigerant in the low-temperature region below 20 K. [ABSTRACT FROM AUTHOR]