Department of Physics and Astronomy: Publications and Other Research
Date of this Version
9-2018
Document Type
Article
Citation
Published in Nano Letters 2018, 18, 7428−7434
DOI: 10.1021/acs.nanolett.8b01789
Abstract
We use nano disk arrays with square and honeycomb symmetry to investigate magnetic phases and spin correlations of XY dipolar systems at the micro scale. Utilizing magnetization sensitive X-ray photoemission electron microscopy, we probe magnetic ground states and the “order-by-disorder” phenomenon predicted 30 years ago. We observe the antiferromagnetic striped ground state in square lattices, and 6-fold symmetric structures, including trigonal vortex lattices and disordered floating vortices, in the honeycomb lattice. The spin frustration in the honeycomb lattice causes a phase transition from a long-range ordered locked phase over a floating phase with quasi long-range order and indications of a Berezinskii−Thouless−Kosterlitz-like character, to the thermally excited paramagnetic state. Absent spatial correlation and quasi periodic switching of isolated vortices in the quasi long-range ordered phase suggest a degeneracy of the vortex circulation.
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Comments
Copyright © 2018 American Chemical Society. Used by permission.