Sökning: "Spin Correlations"

Visar resultat 1 - 5 av 41 avhandlingar innehållade orden Spin Correlations.

  1. 1. Non-Orthogonality and Electron Correlations in Nanotransport : Spin- and Time-Dependent Currents

    Författare :Jonas Fransson; Antti-Pekka Jauho; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; non-orthogonality; non-equilibrium; transport; nanosystem; quantum dot; spin-dependent; renormalization; Green function; diagram technique; many-body states; Hubbard operator; electron correlations; time-dependent; Fysik; icke-ortogonal; icke-jämvikt; transport; nanosystem; kvantprick; spinberoende; renormering; Green-funktion; diagramteknik; mångkropparstillstånd; Hubbadoperator; elektronkorrelationer; tidsberoende; Physics; Fysik; Fysik; Physics;

    Sammanfattning : The concept of the transfer Hamiltonian formalism has been reconsidered and generalized to include the non-orthogonality between the electron states in an interacting region, e.g. quantum dot (QD), and the states in the conduction bands in the attached contacts. LÄS MER

  3. 2. Role of charge and spin fluctuations and their interplay in solids : A Green’s function approach

    Författare :Tor Sjöstrand; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Green’s function; correlations; collective excitations; screened interaction; electric polarization; orbital and spin magnetization; magnon-phonon interaction; Fierz ambiguity; time-dependent exchange-correlation potential;

    Sammanfattning : Due to the large number of electrons, solid state physics boils down to many-body approximations in which only selected types of collective excitations are taken into account, guided by the emergent properties of the material under study. In this thesis, the collective excitations of primary interest are electronic charge and spin fluctuations(plasmons and magnons) and nuclear charge fluctuations (phonons). LÄS MER

  4. 3. Trends in Magnetism : From Strong Correlations to “-onics” Technology

    Författare :Dmitry Yudin; Olle Eriksson; Grigori Volovik; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Strongly interacting electron systems; Spin dynamics; Topological matter; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : Despite of enormous progress in experimental nanophysics theoretical studies of low-dimensional electron systems still remains a challenging task. Indeed, most of the structures are strongly correlated, so that an effective perturbative treatment is impossible due to the lack of a small parameter. LÄS MER

  5. 4. Correlations in Frustrated Magnets : Classical and Quantum Aspects

    Författare :Sergei Isakov; Anders Karlhede; Frederic Mila; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Fysik;

    Sammanfattning : In this thesis, we study three different aspects of the physics of frustrated magnets. First, we study the interplay of thermal and quantum fluctuations in the transverse field frustrated Ising model on the triangular lattice. LÄS MER

  7. 5. Theory of water-proton spin relaxation in complex biological systems

    Författare :Zhiwei Chang; Biofysikalisk kemi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; spin relaxation theory; immobilized macromolecules; magnetic relaxation dispersion; integral longitudinal relaxation rate; stochastic Liouville equations; multi-spin systems; cross-mode relaxation; spectral density functions;

    Sammanfattning : In complex biological systems (e.g. gels, cross-linked proteins and biological tissues), the longitudinal spin relaxation of water protons is primarily induced by exchange-mediated orientational randomization (EMOR) of intra- and intermolecular magnetic dipole-dipole couplings. LÄS MER