Giant Magnetocaloric Effect in Magnets Down to the Monolayer Limit

Abstract 2D magnets can potentially revolutionize information technology, but their potential application to cooling technology and magnetocaloric effect (MCE) in a material down to the monolayer limit remain unexplored. Herein, it is revealed through multiscale calculations the existence of giant MCE and its strain tunability in monolayer magnets such as CrX 3 (X = F, Cl, Br, I), CrAX (A = O, S, Se; X = F, Cl, Br, I), and Fe 3 GeTe 2 . The maximum adiabatic temperature change (), maximum isothermal magnetic entropy change, and specific cooling power in monolayer CrF 3 are found as high as 11 K, 35 µJ m −2 K −1 , and 3.5 nW cm −2 under a magnetic field of 5 T, respectively. A 2% biaxial and 5% a ‐axis uniaxial compressive strain can remarkably increase of CrCl 3 and CrOF by 230% and 37% (up to 15.3 and 6.0 K), respectively. It is found that large net magnetic moment per unit area favors improved MCE. These findings advocate the giant‐MCE monolayer magnets, opening new opportunities for magnetic cooling at nanoscale.