Electric-field-induced magnetic phase transition in (Hf2/3Fe1/3)2COF

Ferromagnetism breaks time-reversal symmetry, while ferroelectricity breaks spatial-inversion symmetry. Their fundamental origins are different. Thus, there are few materials with intrinsic magnetoelectric coupling. In this work, a 2D Janus in-plane ordered magnetic MXene structure, (Hf₂/₃Fe₁/₃)₂COF, has been predicted to exhibit intrinsic magneto-electric coupling properties by density functional theory (DFT) and Monte Carlo simulations. The ground state of (Hf₂/₃Fe₁/₃)₂COF is ferrimagnetic with a net magnetic moment. The Néel temperature of the system is 12 K according to Monte-Carlo simulation. The direction of the magnetic moment can be flipped by applying an external electric field (0.4 eV/Å). When a biaxial compressive strain is applied, the critical electric field changes to -0.1 eV/Å. In summary, we demonstrate that modifying surface functional groups is an effective method to achieve magneto-electric coupling in 2D in-plane ordered magnetic (i-MXenes). Our calculations not only predict a new 2D material with intrinsic magneto-electric coupling properties, but also provide a new strategy for designing 2D materials with magneto-electric coupling properties.