Stray magnetic field imaging of thin exfoliated iron halides flakes

Fernando Meneses, Rongrong Qi, Alexander J. Healey, Yi You, Islay O. Robertson, Sam C. Scholten, Ashok Keerthi, Gary Harrison, Achintya Bera, Hiran Jyothilal, Lloyd C. L. Hollenberg, Boya Radha, Jean-Philippe Tetienne

Research output: Contribution to journalArticlepeer-review

Abstract

Magnetic van der Waals materials are often proposed for use in future spintronic devices, aiming to leverage the combination of long-range magnetic order and near-atomic thinness to produce energy-efficient components. One class of material that has been discussed in this context are the iron halides
FeCl
2
and
FeBr
2
, which are
A
-type antiferromagnets with strong uniaxial magnetocrystalline anisotropy. However, despite characterization of the bulk materials, the possibility for sustaining the magnetic behaviours that would underpin such applications in thin flakes has not been investigated. In this work, we use nitrogen-vacancy center microscopy to quantitatively image magnetism in individual exfoliated flakes of these iron halides, revealing the absence of magnetic remanence, a weak induced magnetization under bias field, and variable behaviour versus temperature. We show that our results are consistent with the antiferromagnetic behavior of the bulk material with a soft ferromagnetic uncompensated layer, indicating that extended (
>
1
µ
m
) ferromagnetic domains are not sustained even at low temperatures (down to 4 K). Finally, we find that the magnetic order is strongly affected by the sample preparation, with a surprising diamagnetic behaviour observed in a thin, hydrated sample.

Original languageUndefined
JournalPhysical Review B
DOIs
Publication statusPublished - 20 Feb 2024

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