Nitrogen-vacancy magnetometry of CrSBr by diamond membrane transfer

TL;DR

This paper introduces a diamond 'dry-transfer' technique for NV magnetometry, enabling nanoscale magnetic imaging of 2D magnets like CrSBr with high precision and without complex sample preparation.

Contribution

The authors develop a novel diamond transfer method to position NV centers close to 2D magnets, allowing direct magnetic field measurements at the monolayer level.

Findings

Successfully measured monolayer magnetization of CrSBr.

Resolved magnetic stray fields at nanoscale with high spatial resolution.

Demonstrated contact-based NV sensing without exfoliation or large magnetic fields.

Abstract

Magnetic imaging using nitrogen-vacancy (NV) spins in diamonds is a powerful technique for acquiring quantitative information about sub-micron scale magnetic order. A major challenge for its application in the research on two-dimensional (2D) magnets is the positioning of the NV centers at a well-defined, nanoscale distance to the target material required for detecting the small magnetic fields generated by magnetic monolayers. Here, we develop a diamond 'dry-transfer' technique, akin to the state-of-the-art 2D-materials assembly methods, and use it to place a diamond micro-membrane in direct contact with the 2D interlayer antiferromagnet CrSBr. We harness the resulting NV-sample proximity to spatially resolve the magnetic stray fields generated by the CrSBr, present only where the CrSBr thickness changes by an odd number of layers. From the magnetic stray field of a single uncompensated ferromagnetic layer in the CrSBr, we extract a monolayer magnetization of $M_\mathrm{CSB}$ = 0.46(2) T, without the need for exfoliation of monolayer crystals or applying large external magnetic fields. The ability to deterministically place NV-ensemble sensors into contact with target materials and detect ferromagnetic monolayer magnetizations paves the way for quantitative analysis of a wide range of 2D magnets assembled on arbitrary target substrates.