Dynamics of open and closed classical and quantum-mechanical spin systems
,
Dynamik offener und geschlossener klassischer und quantenmechanischer Spinsysteme
Staats- und Universitätsbibliothek Hamburg Carl von Ossietzky
Erscheinungsjahr:
2021
Medientyp:
Text
Schlagworte:
Nanomagnetism
Nanoparticle
Stochastic Landau-Lifshitz-Gilbert equation
Spin chain
Dissipation
530: Physik
33.99: Physik: Sonstiges
Magnetismus
Nanopartikel
Landau-Lifšic-Gleichung
Spinkette
Dissipation
ddc:530:
Magnetismus
Nanopartikel
Landau-Lifšic-Gleichung
Spinkette
Dissipation
Beschreibung:
This thesis is dedicated to the theoretical and practical understanding of different influences of interactions on the statical and dynamical properties of classical and quantum spin systems. Systems of interest have been finite temperature arrays of dipolarly coupled superparamagnetic nanoparticles with uniaxial anisotropy, spin chains with short and long range exchange or dipolar interactions, as well as coupled and diagonalized quantum spins in an infinitely large environment at zero temperature, leading to relaxation behavior for the spin system. For the case of the coupled nanoparticles, finite temperature Langevin spin dynamics in the form of stochastic Landau-Lifshitz-Gilbert-Equation simulations were employed and supplemented with analytic modelling of the phase space. The investigation of the spin chains was realized by both spin dynamical and Monte Carlo simulations as well as analytical calculations for the prediction of collinear and non-collinear ground states of the chains. Finally, the study of the relaxation behavior of isolated and coupled quantum spins in a thermal environment was described by a non-Hermitian Hamiltonian generator for the dynamics of pure quantum states.