The importance of the weak: Interaction modifiers in artificial spin ices

The modification of geometry and interactions in two-dimensional magnetic nanosystems has enabled a range of studies addressing the magnetic order, collective low-energy dynamics, and emergent magnetic properties, in e.g. artificial spin ice structures. The common denominator of all these investigations is the use of Ising-like mesospins as building blocks, in the form of elongated magnetic islands. Here we introduce a new approach: single interaction modifiers, using slave-mesospins in the form of discs, within which the mesospin is free to rotate in the disc plane. We show that by placing these on the vertices of square artificial spin ice arrays and varying their diameter, it is possible to tailor the strength and the ratio of the interaction energies. We demonstrate the existence of degenerate ice-rule obeying states in square artificial spin ice structures, enabling the exploration of thermal dynamics in a spin liquid manifold. Furthermore, we even observe the emergence of flux lattices on larger length-scales, when the energy landscape of the vertices is reversed. The work highlights the potential of a design strategy for two-dimensional magnetic nano-architectures, through which mixed dimensionality of mesospins can be used to promote thermally emergent mesoscale magnetic states.Comment: 17 pages, including methods, 4 figures. Supplementary information contains 16 pages and 15 figure

Influence of the magnetic field on the plasmonic properties of transparent Ni anti-dot arrays

Extraordinary optical transmission is observed due to the excitation of surface plasmon polaritons (SPPs) in 2-Dimensional hexagonal anti-dot patterns of pure Ni thin films, grown on sapphire substrates. A strong enhancement of the polar Kerr rotation is recorded at the surface plasmon related transmission maximum. Angular resolved reflectivity measurements under an applied field, reveal an enhancement and a shift of the normalized reflectivity difference upon reversal of the magnetic saturation (transverse magneto-optical Kerr effect-TMOKE). The change of the TMOKE signal clearly shows the magnetic field modulation of the dispersion relation of SPPs launched in a 2D patterned ferromagnetic Ni film

Magnetic order and energy-scale hierarchy in artificial spin ice

In order to explain and predict the properties of many physical systems, it is essential to understand the interplay of different energy-scales. Here we present investigations of the magnetic order in thermalised artificial spin ice structures, with different activation energies of the interacting Ising-like elements. We image the thermally equilibrated magnetic states of the nano-structures using synchrotron-based magnetic microscopy. By comparing results obtained from structures with one or two different activation energies, we demonstrate a clear impact on the resulting magnetic order. The differences are obtained by the analysis of the magnetic spin structure factors, in which the role of the activation energies is manifested by distinct short-range order. This demonstrates that artificial spin systems can serve as model systems, allowing the definition of energy-scales by geometrical design and providing the backdrop for understanding their interplay.Comment: 8 pages, 5 figures (+ supplementary 6 pages, 4 figures

Використання кавітаційних пристроїв в харчовій промисловості

We present a direct experimental investigation of the thermal ordering in an artificial analogue of an asymmetric two-dimensional Ising system composed of a rectangular array of nano-fabricated magnetostatically interacting islands. During fabrication and below a critical thickness of the magnetic material the islands are thermally fluctuating and thus the system is able to explore its phase space. Above the critical thickness the islands freeze-in resulting in an arrested thermalized state for the array. Determining the magnetic state we demonstrate a genuine artificial two-dimensional Ising system which can be analyzed in the context of nearest neighbor interactions

Insulation effects of Icelandic dust and volcanic ash on snow and ice

In the Arctic region, Iceland is an important source of dust due to ash production from volcanic eruptions. In addition, dust is resuspended from the surface into the atmosphere as several dust storms occur each year. During volcanic eruptions and dust storms, material is deposited on the glaciers where it influences their energy balance. The effects of deposited volcanic ash on ice and snow melt were examined using laboratory and outdoor experiments. These experiments were made during the snow melt period using two different ash grain sizes (1 phi and 3.5 phi) from the Eyjafjallajokull 2010 eruption, collected on the glacier. Different amounts of ash were deposited on snow or ice, after which the snow properties and melt were measured. The results show that a thin ash layer increases the snow and ice melt but an ash layer exceeding a certain critical thickness caused insulation. Ash with 1 phi in grain size insulated the ice below at a thickness of 9-15 mm. For the 3.5 phi grain size, the insulation thickness is 13 mm. The maximum melt occurred at a thickness of 1 mm for the 1 phi and only 1-2 mm for 3.5 phi ash. A map of dust concentrations on Vatnajokull that represents the dust deposition during the summer of 2013 is presented with concentrations ranging from 0.2 up to 16.6 g m(-2).Peer reviewe

Topology by Design in Magnetic nano-Materials: Artificial Spin Ice

Artificial Spin Ices are two dimensional arrays of magnetic, interacting nano-structures whose geometry can be chosen at will, and whose elementary degrees of freedom can be characterized directly. They were introduced at first to study frustration in a controllable setting, to mimic the behavior of spin ice rare earth pyrochlores, but at more useful temperature and field ranges and with direct characterization, and to provide practical implementation to celebrated, exactly solvable models of statistical mechanics previously devised to gain an understanding of degenerate ensembles with residual entropy. With the evolution of nano--fabrication and of experimental protocols it is now possible to characterize the material in real-time, real-space, and to realize virtually any geometry, for direct control over the collective dynamics. This has recently opened a path toward the deliberate design of novel, exotic states, not found in natural materials, and often characterized by topological properties. Without any pretense of exhaustiveness, we will provide an introduction to the material, the early works, and then, by reporting on more recent results, we will proceed to describe the new direction, which includes the design of desired topological states and their implications to kinetics.Comment: 29 pages, 13 figures, 116 references, Book Chapte

The Interplay between Dyslexia, Anxiety, and Educational Attainment among Young Adults in Iceland

The chapter will explore the interplay between dyslexia, anxiety, and educational attainment of young adults in Iceland, a small Nordic welfare state, placing emphasis on inclusive education. A survey, representative of 18- to 24-year-olds in Iceland, and qualitative interviews with 10 young adults were used to gain an understanding of the association between being diagnosed with dyslexia, having experienced anxiety, and young people’s education path. Findings from the survey show that being diagnosed with dyslexia was associated with anxiety and educational attainment. However, experiencing anxiety depended on how old the young adults were when they were diagnosed with dyslexia. Those who were diagnosed at an early age did, in general, not show symptoms of anxiety and were more likely to have continued their studies than those who were diagnosed as teenagers. The qualitative interviews supported the survey-results, as participants described how having to read out loud or receive special education caused anxiety and the feeling of exclusion. The findings indicate that providing support for children with reading difficulties, at an early age, can prevent future anxiety and school drop-out. The findings also raise a question on how well the Icelandic school system conforms to the policy of inclusive education

Pesan Moral Islami Dalam Film Le Grand Voyage Karya Ismael Ferroukhi: Sebuah Tinjauan Struktural

Kata kunci : Film, sastra, struktural, pesan moral, Islam.Film merupakan produk budaya yang tidak hanya menjadi hiburan di masyarakat, tetapi juga sebagai sarana penyampaian pesan moral yang mengarifkan. Salah satufilm Perancis yang dianggap menginspirasi adalah film berjudul Le grand voyageyang ditulis dan disutradarai oleh Ismaël Ferroukhi. Film ini bercerita tentang perjalanan seorang muslim keturunan Maroko dan anaknya yang bernama Reda.Mereka menempuh jarak ribuan mil dari Perancis menuju ke kota Makah untukmelaksanakan haji hanya dengan mengendarai sebuah mobil tua. Penelitian inibertujuan untuk mengetahui pesan moral islami apa saja yang terkandung dalamfilm Le grand voyage dan bagaimana pesan tersebut dimunculkan dalam film.Penelitian ini menggunakan teori Struktural untuk menjawab rumusan masalah.Penelitian ini merupakan penelitian kualitatif dengan menggunakan teknik studipustaka serta dokumentasi sebagai metode pengumpulan data, dan teknikdeskriptif dalam proses analisis data.Berdasarkan hasil penelitian ini, terdapat 13 pesan moral islami yang terkandungdalam film Le grand voyage. Semua pesan moral tersebut mengacu pada sebuahproses perbaikan moral dan spiritual antara manusia dengan manusia dan alam,serta antara manusia dengan TuhanPenulis menyarankan pada penelitian selanjutnya untuk meneliti film Le grandvoyage menggunakan pendekatan sosiologi sastra yang nantinya dapat mengupashal apa saja yang melatarbelakangi pembuatan film ini dan tujuan sebenarnyayang ingin dicapai oleh pembuat film Le grand voyage

Multiple energy scales in mesospin systems : the vertex-frustrated Saint George lattice

The interplay between topology and energy hierarchy plays a vital role in the collective magnetic order in artificial ferroic systems. Here we investigate, experimentally, the effect of having one or two activation energies of interacting Ising-like magnetic islands—mesospins—in thermalized, vertex-frustrated lattices. The thermally arrested magnetic states of the elements were determined using synchrotron-based magnetic microscopy after cooling the samples from temperatures above the Curie temperature of the material. Statistical analysis of the correlations between mesospins across several length scales reveals changes in the magnetic order, reflecting the amount of ground state plaquettes realized for a vertex-frustrated lattice. We show that the latter depends on the presence, or not, of different activation energies