Strain effects on the electronic and magnetic properties of Cr₂TaC₂ and Cr₂TaC₂O₂ monolayers

Double transition metal MXene materials, such as Cr2TiAlC2, were successfully synthesized recently in addition to the synthesized mono transition metal MXenes. The physical and chemical properties of the MXenes can be tuned by varying the middle metal layer composition by other metal atoms. Thus, the desired mechanical, electronic, thermal, or magnetic properties can be revealed in that MXene material. The other method to tune material properties is by applying external strain on the structure. In this study, we systematically investigate the physical properties, such as dynamical, thermal, mechanical stability, electronic, and magnetic properties of the Cr2TaC2 and the Cr2TaC2O2 MXene monolayers for equilibrium and under biaxial strain. We find that both of MXene monolayers are energetically, thermally, and dynamically stable for certain compressive and tensile strain values. The Cr2TaC2 and the Cr2TaC2O2 MXene monolayers have a ferromagnetic ground state and show a metallic character in an equilibrium state and preserve it up to high tensile strain (e = 0.10) value. The robust ferromagnetism above room temperature is demonstrated for the Cr2TaC2 with a Curie temperature of 714 K for the strain-free case. This value reduces to 234 K for the Cr2TaC2O2 monolayer. Moreover, our detailed Monte Carlo simulations reveal that the magnetic transition temperature of the system and also hysteresis properties can be controlled by moving from compressive to tensile strain ratios.