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Phase transitions i...
Phase transitions in magnetic metamaterials
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- Skovdal, Björn Erik (författare)
- Uppsala universitet,Materialfysik
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- Hjörvarsson, Björgvin, Professor (preses)
- Uppsala universitet,Materialfysik,Materialteori
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- Kapaklis, Vassilios, Professor, 1978- (preses)
- Uppsala universitet,Materialfysik
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- Pálsson, Gunnar K., Biträdande universitetslektor (preses)
- Uppsala universitet,Materialfysik
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- Schiffer, Peter, Professor (opponent)
- Yale University
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(creator_code:org_t)
- ISBN 9789151314976
- Uppsala : Acta Universitatis Upsaliensis, 2022
- Engelska 62 s.
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Serie: Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 ; 2149
- Relaterad länk:
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Abstract
Ämnesord
Stäng
- Magnetic metamaterials consisting of arrays of densely packed, two-dimensional nanoscale magnetic islands have degrees of freedom on two separate length scales: inside the islands, and among them. These degrees of freedom can be tuned by e.g. size, shape, island separation and lattice geometry. The material can thereby be tailored to display behavior corresponding to conventional universality classes, wherein small elongated islands behave like Ising spins and circular ones behave like XY-spins. Making the islands larger promotes inner degrees of freedom in the form of inner magnetic textures. Some of these textures, such as magnetic vortices in circular islands, have a critical impact on the interaction between the islands and therefore also on the global order.In this thesis, the interplay between the inner textures and island-island interactions is explored, anticipating the emergence of behavior beyond that of conventional universality classes. A transition temperature between static and dynamic inner textureswas found in systems with elongated islands. In arrays of circular islands, a collapse from metastable collinear islands to vortex islands was observed, with a dependence on both island size and lattice orientation. Finally, a model was created based on key aspects of the circular islands, and using Monte Carlo calculations, an exotic phase diagram with a tricritical point and first order phase transitions was found. The transition is caused by a mutual dependence on the degrees of freedom inside, and among the elements. The experimental and numerical results presented in this thesis signify the existence of such phase transitions in the multiscale material.
Ämnesord
- NATURVETENSKAP -- Fysik -- Den kondenserade materiens fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Condensed Matter Physics (hsv//eng)
Nyckelord
- Magnetic metamaterials
- artificial spin ice
- mesospins
- magnetic nanostructures
- mesoscopic spin systems
- multiscale materials
- tri-criticality
- emergence
- edge modes
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