Keynote Speaker
Prof. Dr. Lukas Eng
“Pushing the limits in PFM and MFM”
Lukas M. Eng 1,2 , M. Röper, J. Schmidt 1 , and SD Seddon 1
1 Institute of Applied Physics, TU Dresden, Nöthnitzerstr. 61, 01187 Dresden, Germany
2 ct.qmat: Würzburg-Dresden Cluster of Excellence - EXC 2147, TU Dresden, Germany
Piezoresponse Force Microscopy (PFM) has a 31-year track record [1] and has since witnessed widespread uses to image and manipulate a manifold of polar and ferroic materials [2] including 2D materials [3]. Soon after the initial steps in 1993 realizing vertical (out-of-plane) PFM [1], PFM was extended to simultaneously map the in-plane piezoelectric component [4] as well, and then complemented for full 3D imaging and manipulation [5 ].
I will show in this talk that even today, PFM still provides a lot of challenges and peculiarities: the issue in particular here is the ability of PFM to map into the depth of a sample [6], hence achieving a sub-surface resolution. that will be shown to be mainly determined by the PFM tip radius [7]. That theoretical and experimental work underlines the importance of how to select and prepare adequate dielectric substrates for any PFM-related work, a topic that has been completely overlooked so far.
Moreover, 3D PFM has inspired us to also extend standard vertical (out-of-plane) Magnetic Force Microscopy (V-MFM) for the simultaneous multi-dimensional (3D) mapping of magnetic stray fields. Such 3D fields are everywhere, from the toy magnet up to magnetic Bloch-[8-10], Néel- [11,12] and Anti-Skyrmions [13,14]. By complementing V-MFM with lateral (in-plane) MFM (L-MFM) [15], magnetic stray field gradients can now be mapped in a much more complete way. Results and challenges of 3D MFM by discussing the overall performance and signal-to-noise ratio will be presented here.
References:
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[15] J. Schmidt et al., (2024); https://doi.org/10.48550/arXiv.2308.08377 .