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

Abstract

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 6 K 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.