Synergetic effect of edge states and point defects to tune ferromagnetism in CVD-grown vertical nanostructured MoS2: A correlation between electronic structure and theoretical study

TL;DR

This study investigates how edge states and point defects in nanostructured MoS2 influence room-temperature ferromagnetism, revealing that defect engineering via ion irradiation modulates magnetic properties linked to electronic structure changes.

Contribution

It provides a combined experimental and theoretical analysis of defect-induced ferromagnetism in MoS2, highlighting the role of edge states and oxygen incorporation in magnetic tuning.

Findings

Pristine MoS2 nanosheets exhibit high magnetization of 1.7 emu/g.

Ion irradiation reduces vertical nanosheet integrity and magnetic moment.

Oxygen incorporation at sulfur vacancies alters electronic states and decreases magnetism.

Abstract

Room-temperature ferromagnetism (RTFM) exhibited by nanostructured two-dimensional semiconductors for spintronics applications is a fascinating area of research. The present work reports on the correlation between the electronic structure and magnetic properties of defect-engineered nano-structured MoS2 thin films. Low-energy light and heavy-mass ion irradiation have been performed to create defects and tune magnetic properties. Vertical nanosheets with edge state termination in the pristine sample have been examined by field emission scanning electron microscopy (FESEM). Deterioration of vertical nanosheets is observed in low-energy Ar+ and Xe+ irradiated samples. An appreciably high magnetization value of 1.7 emu/g was observed for edge-oriented nanostructured pristine MoS2 thin films, which decreased after ion irradiation. From X-ray photoelectron spectroscopy (XPS) data, it is evident that, due to oxygen incorporation in the sulfur vacancy sites, Mo5+ and 6+ states increase after ion irradiation. The density functional theory (DFT) calculations suggest that the edge-oriented spins of the prismatic edges of the vertical nanosheets are primarily responsible for the high magnetic moment in the pristine film, and the edge degradation and reduction in sulfur vacancies by the incorporation of oxygen upon irradiation result in a decrease in the magnetic moment.