Sökning: "vortex pinning"

Hittade 5 avhandlingar innehållade orden vortex pinning.

1. 1. Tailored Properties of Ferromagnetic Thin Films

   Författare :Peter Warnicke; Peter Svedlindh; Peter Grünberg; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; micromagnetics; domain wall; vortex; pinning potential; nanowire; spin dynamics; spin transfer torque; magnetic anisotropy; MFM; Permalloy; PMA; magnetic multilayer; Curie temperature; DMS; GaMnAs; magnetic bioseparation; Engineering physics; Teknisk fysik;

   Sammanfattning : Magnetic thin films and patterned nanostructures have been studied with respect to their magnetic properties using SQUID-magnetometry, magnetic force microscopy, electrical measurements, and micromagnetic calculations. Properties of vortex domain walls, trapped in Permalloy nanowires with artificial constrictions, were investigated experimentally and by numerical calculations. LÄS MER

3. 2. Nonlinear dynamics of strongly-bound magnetic vortex pairs

   Författare :Artem Bondarenko; Vladislav Korenivski; Gleb Kakazei; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; magnetic vortex; nonlinear mechanics; isolated resonance; nonlinear frequency tuning; chaotic dynamics; parametric interaction; Thiele equation; Monte Carlo simulations; Ito processes; bistability; tunneling magneto-resistance; Magnetisk-virvel; icke-linjär dynamik; isolerad resonans; icke-linjär frekvens-optimering; kaotisk dynamik; parametrisk interaktion; Thiele-ekvation; Monte Carlo-simuleringar; Ito-processer; bistabilitet; tunnelmagneto-resistans.; Fysik; Physics;

   Sammanfattning : This work is a study of nonlinear phenomena in vertically stacked pairs of magnetic vortices. New dynamic regimes are uncovered with a decrease in the inter-vortex separation to below the lateral vortex-core size. LÄS MER

4. 3. Phase transitions in novel superfluids and systems with correlated disorder

   Författare :Hannes Meier; Mats Wallin; Asle Sudbø; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; condensed matter physics; phase transitions; critical phenomena; spin models; quantum phase transitions; quantum fluids; superfluidity; superconductivity; disordered systems; Bose glass; dirty bosons; vortex pinning; statistical mechanics; Monte Carlo simulation; Wolff algorithm; classical worm algorithm; Wang-Landau algorithm; Fysik; Physics;

   Sammanfattning : Condensed matter systems undergoing phase transitions rarely allow exact solutions. The presence of disorder renders the situation  even worse but collective Monte Carlo methods and parallel algorithms allow numerical descriptions. LÄS MER

5. 4. Resonant vortex-pair dynamics and magnetocalorics in magnetic nanostructures

   Författare :Erik Holmgren; Vladislav Korenivski; Gisela Schütz; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Fysik;

   Sammanfattning : This thesis investigates the dynamics of spin vortex pairs in nanopillars andthermal effects in magnetic multilayers with RKKY-like indirect exchange.Spin vortices are being investigated as storage elements for memory applicationsas well as for GHz oscillators and signal processing devices. LÄS MER

7. 5. From Order to Disorder in High Temperature Superconductors

   Författare :Anders Vestergren; KTH; []
   Nyckelord :physics; condensed matter;

   Sammanfattning : Phase transitions in a number of models related to hightemperature superconductors are investigated, using scalingmethods and Monte Carlo simulations. This thesis considers twomain topics. LÄS MER