Sökning: "Second-order magnetic phase transition"

Hittade 5 avhandlingar innehållade orden Second-order magnetic phase transition.

  1. 1. Direct and indirect magnetocaloric properties of first- and second-order phase transition materials

    Författare :Sagar Ghorai; Peter Svedlindh; Martin Sahlberg; Gabriella Andersson; Ekkes Brück; Uppsala universitet; []
    Nyckelord :Magnetocaloric effect; Adiabatic temperature change; Direct measurement of magnetocaloric effect; Griffiths phase; Magneto-elastic transition; Magneto-structural transition; Second-order magnetic phase transition; First-order magnetic phase transition; Isothermal magnetic entropy change; Fysik; Physics;

    Sammanfattning : The energy-efficient and environmentally friendly alternative cooling technology based on the magnetocaloric effect (MCE) is discussed in this thesis. The thesis has two major parts, one devoted to material characterization and the other to instrument development. LÄS MER

  3. 2. Resistivity and the solid-to-liquid transition in high-temperature superconductors

    Författare :Beatriz Espinosa Arronte; Magnus Andersson; Charles Simon; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; high-temperature superconductors; vortex dynamics; vortex solid-to-liquid transition; critical scaling; glass transition; Bose glass; heavy-ion irradiation; YBCO; Tl2Ba2CaCu2O8 d; oxygen deficiency.; Condensed matter physics; Kondenserade materiens fysik;

    Sammanfattning : In high-temperature superconductors a large region of the magnetic phase diagram is occupied by a vortex phase that displays a number of exciting phenomena. At low temperatures, vortices form a truly superconducting solid phase which at high temperatures turns into a dissipative vortex liquid. LÄS MER

  4. 3. Theoretical Description of the Electron-Lattice Interaction in Molecular and Magnetic Crystals

    Författare :Elham Mozafari; Igor A. Abrikosov; Sven Stafström; George Malcolm Stocks; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Molecular crystals; Charge transport; Polaron; Magnetic materials; Paramagnetic state; Molecular dynamics;

    Sammanfattning : Electron-lattice interactions are often considered not to play a major role in material's properties as they are assumed to be small, the second-order effects. However, this study shows the importance of taking these effects into account in the simulations. LÄS MER

  5. 4. Structure and Dynamics in Transition Metal Perovskites — An Optical Spectroscopy Study

    Författare :Johan Bielecki; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; multiferroics; colossal magnetoresistance; magnetism; proton-conduction; spin-state transition; structure; Ultrafast spectroscopy; high temperature superconductivity; dynamics; Raman;

    Sammanfattning : Transition metal oxides with the perovskite structure exhibit a vast number of exotic properties due to the large number of competing degrees of freedom at the Fermi surface. Together with couplings between and correlations within these degrees of freedom, this class of materials is of high interest from both a practical and theoretical point of view. LÄS MER

  7. 5. Exploring magnetocaloric materials by ab-initio methods

    Författare :Rafael Martinho Vieira; Heike C. Herper; Torbjörn Björkman; Olle Eriksson; Markus Gruner; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; magnetocaloric; magnetism; ab-initio;

    Sammanfattning : This thesis explores the characterization of magnetocaloric materials from first-principles calculations, emphasizing entropy variation associated with the magnetocaloric effect. The study happens in the context of the search for new magnetocaloric materials to be applied in domestic magnetic refrigerators,  as environmentally friendly and energy-efficient alternatives to conventional vapor-compression devices. LÄS MER