| 1. |
- Ray, S. J., et al.
(författare)
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Muon-spin rotation measurements of the vortex state in Sr2RuO4 : Type-1.5 superconductivity, vortex clustering, and a crossover from a triangular to a square vortex lattice
- 2014
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 89:9, s. 094504-
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Tidskriftsartikel (refereegranskat)abstract
- Muon-spin rotation has been used to probe the vortex state in Sr2RuO4. At moderate fields and temperatures a lattice of triangular symmetry is observed, crossing over to a lattice of square symmetry with increasing field and temperature. At lower fields it is found that there are large regions of the sample that are completely free from vortices which grow in volume as the temperature falls. Importantly this is accompanied by increasing vortex density and increasing disorder within the vortex-cluster-containing regions. Both effects are expected to result from the strongly temperature-dependent long-range vortex attractive forces arising from the multiband chiral-order superconductivity.
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| 2. |
- Garaud, Julien, et al.
(författare)
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Skyrmions induced by dissipationless drag in U(1)xU(1) superconductors
- 2014
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 89:10, s. 104508-
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Tidskriftsartikel (refereegranskat)abstract
- Rather generically, multicomponent superconductors and superfluids have intercomponent current-current interaction. We show that in superconductors with substantially strong intercomponent drag interaction, the topological defects which form in an external field are characterized by a skyrmionic topological charge. We then demonstrate that they can be distinguished from ordinary vortex matter by a very characteristic magnetization process due to the dipolar nature of inter-skyrmion forces. The results provide an experimental signature to confirm or rule out the formation p-wave state with reduced spin stiffness in p-wave superconductors.
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| 3. |
- Herland, Egil V., et al.
(författare)
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Phase structure and phase transitions in a three-dimensional SU(2) superconductor
- 2013
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 87:13, s. 134503-
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Tidskriftsartikel (refereegranskat)abstract
- We study the three-dimensional SU(2)-symmetric noncompact CP1 model, with two charged matter fields coupled minimally to a noncompact Abelian gauge field. The phase diagram and the nature of the phase transitions in this model have attracted much interest after it was proposed to describe an unusual continuous transition associated with deconfinement of spinons. Previously, it has been demonstrated for various two-component gauge theories that weakly first-order transitions may appear as continuous ones of a new universality class in simulations of relatively large, but finite systems. We have performed Monte Carlo calculations on substantially larger systems sizes than those in previous works. We find that in some area of the phase diagram where at finite sizes one gets signatures consistent with a single first-order transition; in fact, there is a sequence of two phase transitions with an O(3) paired phase sandwiched in between. We report (i) a new estimate for the location of a bicritical point and (ii) the first resolution of bimodal distributions in energy histograms at relatively low coupling strengths. We perform a flowgram analysis of the direct transition line with rescaling of the linear system size in order to obtain a data collapse. The data collapses up to coupling constants where we find bimodal distributions in energy histograms.
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| 4. |
- Sellin, Karl A. H., et al.
(författare)
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Stripe, gossamer, and glassy phases in systems with strong nonpairwise interactions
- 2013
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1539-3755 .- 1550-2376. ; 88:4, s. 042305-
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Tidskriftsartikel (refereegranskat)abstract
- We study structure formation in systems of classical particles in two dimensions with long-range attractive short-range repulsive two-body interactions and repulsive three-body interactions. Stripe, gossamer, and glass phases are found as a result of nonpairwise interaction.
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| 5. |
- Varney, Christopher N., et al.
(författare)
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Hierarchical structure foramtion in layered superconducting systems with multi-scale inter-vortex interactions
- 2013
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 25:41, s. 415702-
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the formation of hierarchical structures in two-dimensional systems with multiple length scales in the inter-particle interaction. These include states such as clusters of clusters, concentric rings, clusters inside a ring, and stripes in a cluster. We propose to realize such systems in vortex matter (where a vortex is mapped onto a particle with multi-scale interactions) in layered superconducting systems with varying inter-layer thicknesses and different layer materials.
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