Large magnetocaloric refrigeration performance near room temperature in monolayer transition metal dihalides.

This article investigates the magnetocaloric effect (MCE) in two-dimensional (2D) transition metal dihalides MX₂ (M = Fe, Ru, Os; X = Cl, Br) as promising materials for solid-state refrigeration near room temperature. It identifies FeCl₂, FeBr₂, and RuCl₂ as exhibiting notably large isothermal magnetic entropy change (−ΔS_mag^max), adiabatic temperature change (ΔT_ad^max), and high lattice thermal conductivity, which contribute to superior refrigeration performance compared to other 2D magnets. The study reveals that strong nearest-neighbor ferromagnetic exchange interactions primarily determine the magnetocaloric properties, while moderate strain and carrier doping effectively tune the Curie temperature and magnetocrystalline anisotropy energy, enhancing the MCE. These findings highlight the potential of MX₂ monolayers for environmentally friendly, efficient nanoscale thermal management applications.