Zigzag antiferromagnetic property of two-dimensional NiPX3 (X = S/Se) monolayers in their pristine structure and Janus phase†

Transition metal phosphorous trichalcogenides TMPX₃ (TM = transition metal, X = S/Se) with a variety of spin configurations serve as excellent platforms for studying the magnetic properties of two-dimensional systems. As an antiferromagnetic semiconductor, the coexistence of ferromagnetic and antiferromagnetic couplings between the nearest neighboring metal ions of NiPX₃ remains a debatable topic. In this work, the electronic structures and magnetic properties of NiPX₃ monolayers in their pristine structure and Janus phase were systemically investigated using first-principles calculations. It was found that the NiPX₃ system possessed an indirect band gap in the zigzag antiferromagnetic ground state with a sizable Néel temperature, as estimated by Monte Carlo simulations. Electronic structures and crystal orbital Hamilton population analyses revealed that the zigzag antiferromagnetic ordering was primarily driven by superexchange interactions through p–d hybridization. Meanwhile, the coexistence of ferromagnetic and antiferromagnetic couplings was facilitated through a combination of antibonding and bonding states below the Fermi level. This work provides a new approach to explore the diverse and intriguing magnetic properties of two-dimensional materials.