Anisotropic magnetocaloric effect of CrI$_{3}$: A theoretical study

A promising candidate for van-der-Waals magnetic materials such as CrI$_{3}$ for spintronic devices and data storage has attracted considerable attention. In the present study, we derived the Heisen- berg Hamiltonian for CrI3 from density functional calculations using the Liechtenstein formula. Monte–Carlo simulations with the Sucksmith–Thompson method were performed to analyze the effect of magnetic anisotropy energy on the thermodynamic properties. Our method successfully reproduced the negative sign of isothermal magnetic entropy changes when a magnetic field was applied along the hard plane. We found that the temperature dependence of the magnetocrystalline anisotropy energy is not negligible at temperatures slightly above the Curie temperature. We clarified that the origin of this phenomenon is anisotropic magnetic susceptibility and magnetization anisotropy. The difference between the entropy change curves of the easy axis and the hard plane is caused by the temperature dependence of the magnetic anisotropy energy. The energy barrier reduction as magnetic anisotropy energy at finite temperature mainly comes from the entropic term since it tends to maximize the randomness of the magnetization in both direction and value.