Ptychographic nanoscale imaging of the magnetoelectric coupling in freestanding BiFeO$_3$

Tim A. Butcher, Nicholas W. Phillips, Chun-Chien Chiu, Chia-Chun Wei, Sheng-Zhu Ho, Yi-Chun Chen, Erik Fröjdh, Filippo Baruffaldi, Maria Carulla, Jiaguo Zhang, Anna Bergamaschi, Carlos A. F. Vaz, Armin Kleibert, Simone Finizio, Jan-Chi Yang, Shih-Wen Huang, Jörg Raabe
Condensed Matter, Materials Science, Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
2023-08-24 16:00:00
Soft X-ray ptychography was employed to simultaneously image the ferroelectric and antiferromagnetic domains in an 80 nm thick freestanding multiferroic BiFeO$_3$. The antiferromagnetic spin cycloid was resolved by reconstructing the resonant elastic X-ray scattering and visualised together with mosaic-like ferroelectric domains in a linear dichroic contrast image at the Fe L$_3$ edge. The measurements reveal a near perfect coupling between the magnetic and ferroelectric ordering by which the propagation direction of the spin cycloid is locked orthogonally to the ferroelectric polarisation. The results provide a direct visualisation of the strong magnetoelectric coupling in BiFeO$_3$ and of its fine multiferroic domain structure, emphasising the potential of high resolution ptychographic imaging in opening new possibilities for the study of multiferroics and non-collinear magnetic materials with soft X-rays.
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