Giant Room-Temperature Magnetocaloric Effect in Two-Dimensional Ternary Transition Metal Chalcogenides

We investigate the magnetic exchange interaction, magnetic anisotropy (MAE), and magnetocaloric effect (MCE) of ternary transition metal chalcogenides A 2 MX 4 (A = Ti or V; M = W or Mo; X = S or Se). We find that Ti 2 WS 4 and Ti 2 WSe 4 exhibit large entropy changes of 5.97 and 5.51 μJ m –2 K –1, respectively, under a magnetic field near room temperature. Analysis based on perturbation theory indicates that strong second-nearest-neighbor exchange coupling plays an important role in MCE, along with a large MAE of ∼10 meV that is attributed to the coupling contributions of d x 2 – y 2 and d z 2 orbitals of the W atom. Moreover, strain and carrier doping effectively modulate the MAE and Curie temperature, leading to remarkable enhancement of the MCE. This work provides important insights into the design of two-dimensional materials with enhanced MCE and is expected to facilitate further advancements in room-temperature magnetic refrigeration for practical applications.