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Lecture Weida Wu


01 August 2012 FWN-Building 5115.0017, Nijenborgh 4, 9747 AG, Groningen
Speaker: Prof. Dr. Weida Wu
Affiliation: Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Piscataway, NJ, USA
Title: Magnetism at ferroelectric domain walls in multiferroic hexagonal manganites
Date: Wed Aug 1, 2012
Start: 11.00
Location: FWN-Building 5115.0017
Host: Maxim Mostovoy
Telephone: +31 50 363 3419



Topological defects are pervasive in complex matter such as superfluids, liquid crystals, and early universe. They have been fruitful playgrounds for many emergent phenomena. Recently, vortex-like topological defects with six interlocked structural antiphase and ferroelectric domains merging into a vortex core were revealed in ferroelectric hexagonal manganites [1]. Numerous vortices are found to form an intriguing self-organized network, where charged domain walls with emergent properties are protected. Using cryogenic magnetic force microscopy (MFM) in applied magnetic fields and ambient piezo-response force microscopy (PFM), we discovered that the alternating domain wall magnetizations around vortices can correlate over the entire vortex network in ErMnO3 [2]. The “collective” nature of the domain wall magnetism appears originated from the uncompensated Er3+ moments at domain walls, the field-controllable spin state of antiferromagnetic domains, and the correlated organization of the vortex network. Our results demonstrate a new route for nanoscale magnetoelectric coupling in single-phase multiferroics, and open the possibility of detecting spin state by harnessing domain wall magnetism.


[1] T. Choi et al., Nature Materials 9, 253 (2010).

[2] Y. Geng, N. Lee, Y. J. Choi, S.-W. Cheong, and W. Wu, arXiv:1201.0694  (2012).

Last modified:22 October 2012 2.30 p.m.