Imaging antiferromagnetic spin cycloids in bismuth ferrite (BiFeO3)

Antiferromagnets are magnetically ordered materials, where the directions of the atomic magnetic moments alternate, resulting in net macroscopic magnetization which is nominally zero. Beyond their fundamental interest, antiferromagnets present attractive features for future spintronic applications. 

It is largely overlooked that these seemingly exotic materials are in fact widespread – a 90% majority of known magnets present such antiferromagnetic order. Well-studied examples include many metal-oxides, manganese-based alloys and rock salts as well as halides. Yet, the real-space observation of antiferromagnetic order remains a challenging task, in particular at the nanoscale.

It was recently realized that highsensitivity magnetic imaging of the stray fields (also known as demagnetizing fields) outside the material offers a powerful avenue to address nanoscale spin textures in antiferromagnets.

In this Application Note, we show how Qnami ProteusQ™ can be used to image antiferromagnetic spin textures with state-of-the-art accuracy. We present two modes of operation allowing to rapidly converge towards quantitative understanding of the magnetic textures at the surface of an antiferromagnet. We use BiFeO3 as a prototype example, where we reveal spin cycloidal antiferromagnetic order with a performance that compares favorably with the recent literature.

Application note (PDF)

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