NiVCl 2 Monolayer: A Robust Topological Nodal Loop Semimetal with a High Curie Temperature

Two-dimensional (2D) magnetic topological materials have attracted significant attention due to their unique advantages in spintronics and topological quantum computing. In this work, we predicted one type of stable 2D topological material, the NiVCl 2 monolayer, by performing density functional theory (DFT) calculations. Our results demonstrate that the NiVCl 2 monolayer is a robust ferrimagnetic (FiM) nodal-loop semimetal (NLSM) characterized by a nodal loop near the Fermi level. Moreover, the nodal loop is found to be protected by three vertical mirror symmetries, and a tiny band gap opens when the magnetization direction is normal to the plane. Furthermore, the system undergoes a phase transition from a FiM NLSM to an antiferromagnetic (AFM) semiconductor (SC) under a biaxial compressive strain of −3%. This discovery paves a new way for manipulating magnetic topological materials and holds great promise for applications in low-power spintronic devices.