Robust room-temperature ferromagnetism induced by defect engineering in monolayer MoS2

Abstract

Magnetism in two-dimensional materials is of great importance for exploring new physical phenomena and developing novel devices in nanoscale. It’s still a challenge to induce robust room temperature ferromagnetism in monolayer transition metal dichalcogen compound materials. In this paper, high quality monolayer MoS2 was prepared by chemical vapor deposition and low energy Cu ions were implanted into MoS2 via ion implantation. The surface morphology, chemical states, optical and magnetic properties were systematically investigated. Robust room-temperature ferromagnetism with saturation magnetization as high as 58 μB/Cu (∼2148 emu/cm3) was successfully induced in monolayer MoS2 after Cu implantation. Moreover, the magnetic properties are weakly temperature dependent, which is clearly the characteristic of defect-induced magnetism. First principles density functional theory calculations reveal that various structural defects, including nanohole, CuMo, Cui + VS and CuMo + VS can induce high magnetic moments. Meanwhile, CuMo and Cui + VS have lower formation energies and may contribute significantly to the extremely large magnetism in the implanted monolayer MoS2. Our work has demonstrated that through defects engineering by Cu implantation, robust room temperature ferromagnetism can be achieved in monolayer MoS2, which provides a potential way to induce large magnetization in other transition metal dichalcogen compound materials, and opens up new opportunities for their applications in nano-spintronics.