Intrinsic piezoelectric ferromagnetism with large out-of-plane piezoelectric response in Janus monolayer CrB r 1.5 I 1.5

A two-dimensional (2D) material system with both piezoelectric and ferromagnetic (FM) orders, referred to as a 2D ferromagnetism (PFM), may open up unprecedented opportunities for intriguing physics. Inspired by experimentally synthesized Janus monolayer MoSSe from MoS2, in this work, the CrBr1.5I1.5 dynamic, mechanical, thermal stabilities is predicted, which constructed CrI3 replacing top I atomic layer Br atoms. Calculated results show that an intrinsic FM half semiconductor valence conduction bands being fully spin-polarized same spin direction. Furthermore, possesses sizable magnetic anisotropy energy. By symmetry analysis, it found in-plane out-of-plane polarizations can be induced uniaxial strain basal plane. The calculated d22 value of 0.557 pm/V small. However, more excitingly, d31 high 1.138 pm/V, obviously higher compared other known materials. strong piezoelectricity highly desirable ultrathin devices. Moreover, engineering used tune CrBr1.5I1.5. It compressive improve tensile enhance d31. order antiferromagnetic phase transition strain, critical point about 0.95 strain. That say antiferromagnetism achieved corresponding are 0.677 0.999 at 0.94 respectively. also has important effects on Finally, similar CrBr1.5I1.5, PFM realized monolayers CrF1.5I1.5 CrCl1.5I1.5. Amazingly, their reach 2.578 1.804 Our paper proposes realistic way achieve large d31, making these systems very promising multifunctional spintronic applications.