Nitrogen-Vacancy Magnetometry of Edge Magnetism in WS2 Flakes

TL;DR

This study uses quantum diamond magnetometry to directly image and analyze edge-localized magnetism in WS2 flakes, revealing edge magnetization and its potential for 2D spintronics applications.

Contribution

It provides the first direct imaging evidence of edge magnetism in WS2 flakes at room temperature using NV magnetometry, supporting their use in 2D spintronics.

Findings

Edge-localized stray magnetic fields observed at WS2 flake edges.

Magnetic fields scale linearly with external magnetic field up to 220 mT.

Edge magnetization likely aligned with a tilted axis, indicating spin canting.

Abstract

Two-dimensional (2D) magnets are of significant interest both as a platform for exploring novel fundamental physics and for their potential in spintronic and optoelectronic devices. Recent bulk magnetometry studies have indicated a weak ferromagnetic response in WS2, and theoretical predictions suggest edge-localized magnetization in flakes with partial hydrogenation. Here, we use room-temperature wide-field quantum diamond magnetometry to image pristine and Fe-implanted WS2 flakes of varying thicknesses (45-160 nm), exfoliated from bulk crystals and transferred to NV-doped diamond substrates. We observe direct evidence of edge-localized stray magnetic fields, which scale linearly with applied external magnetic field (4.4-220 mT), reaching up to 4.7 uT. The edge signal shows a limited dependence on the flake thickness, consistent with dipolar field decay and sensing geometry. Magnetic simulations using five alternative models favor the presence of edge magnetization aligned along an axis slightly tilted from the normal to the WS2 flake plane, consistent with spin canting in antiferromagnetically coupled edge states. Our findings establish WS2 as a promising platform for edge-controlled 2D spintronics.