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Skyrmion Lattices in Chiral Metal–organic Frameworks

preprint
submitted on 19.06.2020 and posted on 23.06.2020 by Emma Wolpert, François-Xavier Coudert, Andrew Goodwin

Skyrmions are knot-like topologically-protected objects of use in data storage and low-energy smart devices. They can be generated by applying a magnetic field to certain chiral ferromagnets, with the knotted state involving a curling of the underlying magnetisation to give a nonzero winding number. Here we explore the possibility that chiral metal–organic frameworks (MOFs) might in principle host skyrmionic phases—realised not through the winding of magnetic spins but through that of guest molecule orientations. We propose a simple model for the interactions governing guest orientational order in chiral MOFs, with uniaxial strain acting as conjugate field. Using Monte Carlo simulations we show that this model gives a rich phase behaviour that includes molecular skyrmion crystals. Ab initio molecular dynamics simulations carried out for a candidate chiral MOF of tractable complexity demonstrate that our simple model effectively captures its underlying energetics. Our results suggest that skyrmionic states may indeed be realisable in MOFs and related porous media and may even arise spontaneously in thin-film samples.

Funding

The Complexity Revolution: Exploiting Unconventional Order in Next-Generation Materials Design

European Research Council

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Materials with Targeted Responsive Behavior – MataReB

Agence Nationale de la Recherche

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History

Email Address of Submitting Author

andrew.goodwin@chem.ox.ac.uk

Institution

University of Oxford

Country

UK

ORCID For Submitting Author

0000-0001-9231-3749

Declaration of Conflict of Interest

No conflict of interest

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