Giant Room-Temperature Magnetocaloric Effect in Two-Dimensional Ternary Transition Metal Chalcogenides
Yangjun Hou1, Xiong Xu1, Guangwei Zhai1
1School of Physics, Hunan Key Laboratory of Super Microstructure and Ultrafast Process, Hunan Key Laboratory of Nanophotonics and Devices, State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China.
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We investigate the magnetic exchange interaction, magnetic anisotropy (MAE), and magnetocaloric effect (MCE) of ternary transition metal chalcogenides A2MX4 (A = Ti or V; M = W or Mo; X = S or Se). We find that Ti2WS4 and Ti2WSe4 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 dx2-y2 and dz2 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.
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