Sökning: "XY model"

Visar resultat 6 - 10 av 18 avhandlingar innehållade orden XY model.

1. 6. Collective properties of magnetic mesospins

   Författare :Erik Östman; Björgvin Hjörvarsson; Vassilios Kapaklis; Nicolas Rougemaille; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; artificial spin ice; magnetic nano-structures; mesoscopic spin systems; mesospins; mixed spin dimensionalities; interaction modifier; engineering of energy landscape; emergence;

   Sammanfattning : Mesoscopic spin systems consist of an ensemble of lithographically patterned nanomagnetic elements - mesospins. The interactions between the mesospins, can be designed at will by altering their lateral arrangement, enabling the study of collective magnetic order in a wide range of systems. LÄS MER

3. 7. Magnetic materials with tunable thermal, electrical, and dynamic properties : An experimental study of magnetocaloric, multiferroic, and spin-glass materials

   Författare :Matthias Hudl; Per Nordblad; DD Sarma; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Magnetocalorics; multiferroics; spin glasses; magnetization; polarization; spin-dimensionality; Fasta tillståndets fysik; Solid State Physics;

   Sammanfattning : This thesis concerns and combines the results of experimental studies of magnetocaloric, multiferroic and spin-glass materials, using SQUID magnetometry as the main characteriza-tion technique. The magnetocaloric effect offers an interesting new technology for cooling and heating applications. LÄS MER

4. 8. Interactions and Interference in Mesoscopic Systems: Josephson Current through Quantum Dots and Josephson Junction Arrays

   Författare :Klas Engström; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; density functional theory; quantum dots; Josephson effect; Andreev reflection; mesoscopic superconductivity; Josephson junction array; coulomb interactions; Bogoliubov-de Gennes equation; quantum phase transition;

   Sammanfattning : The focus of the thesis is on the interplay between interactions and interference effects in mesoscopic systems. More specifically, the two main projects included deal with Coulomb interactions and Josephson effect in two superconductor-normal metal systems: (i) a Josephson junction array and (ii) a superconductor-normal metal-superconductor (SNS) system in which the normal part is a quantum dot. LÄS MER

5. 9. Phase transitions in magnetic metamaterials

   Författare :Björn Erik Skovdal; Björgvin Hjörvarsson; Vassilios Kapaklis; Gunnar K. Pálsson; Peter Schiffer; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Magnetic metamaterials; artificial spin ice; mesospins; magnetic nanostructures; mesoscopic spin systems; multiscale materials; tri-criticality; emergence; edge modes;

   Sammanfattning : 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. LÄS MER

7. 10. Molecular mechanisms in disorders of gonadal development

   Författare :Ameli Norling; Karolinska Institutet; Karolinska Institutet; []
   Nyckelord :;

   Sammanfattning : Controlling fertility, or rather infertility, is a common problem for couples nowadays where approximately 10% experience infertility. This thesis focuses on the rare conditions leading to infertility in which the gonads have either failed to develop properly, or prematurely lost their function. LÄS MER