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Robust metastable skyrmions and their triangular–square lattice structural transition in a high-temperature chiral magnet

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Karube K., White J. S., Reynolds N., Gavilano J. L., Oike H., Kikkawa A., Kagawa F., Tokunaga Y., Rønnow H. M., Tokura Y., Taguchi Y.,
Project Exploration of emerging magnetoelectric coupling effects in new materials
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Original article (peer-reviewed)

Journal Nature Materials
Volume (Issue) 15(12)
Page(s) 1237 - 1242
Title of proceedings Nature Materials
DOI 10.1038/nmat4752


Skyrmions, topologically protected nanometric spin vortices, are being investigated extensively in various magnets. Among them, many structurally chiral cubic magnets host the triangular-lattice skyrmion crystal (SkX) as the thermodynamic equilibrium state. However, this state exists only in a narrow temperature and magnetic-field region just below the magnetic transition temperature Tc, while a helical or conical magnetic state prevails at lower temperatures. Here we describe that for a room-temperature skyrmion material, beta-Mn-type Co8Zn8Mn4, a field-cooling via the equilibrium SkX state can suppress the transition to the helical or conical state, instead realizing robust metastable SkX states that survive over a very wide temperature and magnetic-field region. Furthermore, the lattice form of the metastable SkX is found to undergo reversible transitions between a conventional triangular lattice and a novel square lattice upon varying the temperature and magnetic field. These findings exemplify the topological robustness of the once-created skyrmions, and establish metastable skyrmion phases as a fertile ground for technological applications.