Electric-field-induced magnetic phase transition in (Hf_2/3Fe_1/3)₂COF

Ferromagnetism breaks time-reversal symmetry, while ferroelectricity breaks spatial-inversion symmetry. Their fundamental origins are different. Thus, there are few materials that exhibit intrinsic magnetoelectric coupling. In this work, a 2D Janus in-plane ordered magnetic MXene structure, (Hf_2/3Fe_1/3)₂COF, has been predicted to exhibit intrinsic magneto-electric coupling properties by density functional theory (DFT) and Monte Carlo simulations. The ground state of (Hf_2/3Fe_1/3)₂COF is ferrimagnetic with a net magnetic moment. According to Monte Carlo simulations, the Néel temperature of the system is 12 K. The direction of the magnetic moment can be switched by applying an external electric field of 0.4 eV Å^-1. When a biaxial compressive strain is applied, the critical electric field changes to -0.1 eV Å^-1. In summary, we demonstrate that modifying surface functional groups is an effective method to achieve magneto-electric coupling in 2D in-plane ordered magnetic structures (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 magnetoelectric coupling.