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Melting artificial spin ice
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
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2012 (English)In: New Journal of Physics, ISSN 1367-2630, Vol. 14, 035009- p.Article in journal (Refereed) Published
Abstract [en]

Artificial spin ice arrays of micromagnetic islands are a means of engineering additional energy scales and frustration into magnetic materials. Here we demonstrate a magnetic phase transition in an artificial square spin ice and use the symmetry of the lattice to verify the presence of excitations far below the ordering temperature. We do this by measuring the temperature dependent magnetisation in different principal directions and comparing with simulations of idealised statistical mechanical models. Our results confirm a dynamical pre-melting of the artificial spin ice structure at a temperature well below the intrinsic ordering temperature of the island material. We thus create a spin ice array that has real thermal dynamics of the artificial spins over an extended temperature range.

Place, publisher, year, edition, pages
2012. Vol. 14, 035009- p.
Keyword [en]
artificial spin ice, ising model, magnetization dynamics
National Category
Other Physics Topics
Research subject
Physics of Matter
URN: urn:nbn:se:uu:diva-168982DOI: 10.1088/1367-2630/14/3/035009ISI: 000302342000002OAI: oai:DiVA.org:uu-168982DiVA: diva2:504579
Swedish Research Council
Available from: 2012-02-21 Created: 2012-02-21 Last updated: 2012-08-01Bibliographically approved
In thesis
1. Magnetic Order in Artificial Structures
Open this publication in new window or tab >>Magnetic Order in Artificial Structures
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The topic of this thesis is the investigation of the magnetic properties of artificially created magnetic structures. Applying different characterization techniques, ranging from direct imaging methods to reciprocal space techniques, the properties of lithographically patterned arrays of magnetic thin film and multilayer elements are investigated by exploring their magnetic state, extending from the atomic scale up to collective ordering phenomena of nano-magnetic elements.

Laterally patterned amorphous multilayer arrays of combined circular and ellipsoidal islands were investigated. The arrays contain a variety of length scales, ranging from their nanometer scale multilayer structure to their lateral periodicity in the micrometer range. The attributes of these arrays are explored using different techniques, applicable for addressing the magnetization at different length scales, including magneto-optical techniques, micromagnetic simulations and x-ray resonant magnetic scattering.

Arrays of dipole interacting elongated magnetic elements composed of Pd(Fe) thin films were investigated. Pd(Fe) films have a low Curie temperature which can be tuned by the thickness of the Fe layer embedded in Pd. By this, the interaction and the shape anisotropy energies can be brought down to energy scales comparable to room temperature enabling the possibility of investigating the effect of thermal excitations on such arrays. The temperature dependent magnetization of an artificial square spin ice array was investigated by magneto-optical measurements demonstrating the possibility of observing an order-disorder transition in an artificial square spin ice system. The role of dipolar interactions and the possibility of achieving thermal ground state ordering was then further investigated by magnetically sensitive photoemission electron microscopy imaging of ring arrangements of elongated Pd(Fe) elements. The results reveal a high probability of achieving a thermal ground state ordering of the magnetization of the islands.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 65 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 922
National Category
Condensed Matter Physics
urn:nbn:se:uu:diva-172386 (URN)978-91-554-8339-5 (ISBN)
Public defence
2012-05-24, Häggsalen, Ångströmlaboratoriet, Uppsala, 10:15 (English)
Available from: 2012-05-03 Created: 2012-04-10 Last updated: 2012-08-01Bibliographically approved

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Kapaklis, VassiliosArnalds, UnnarPapaioannou, EvangelosKorelis, PanagiotisTaroni, AndreaHjörvarsson, Björgvin
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