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Identifier

000433856

Title

Aspects of the dynamics of the one-dimensional XXZ Heisenberg spin chain

Alternative Title

Πτυχές της δυναμικής στο μονοδιάστατο μοντέλο Heisenberg

Author

Παυλής, Αλέξανδρος

Thesis advisor

Ζώτος, Ξενοφών

Abstract

This thesis is devoted to the study of fundamental aspects of the dynamics of the one-dimensional S=1/2 XXZ model. In particular, we study the scattering of a spinon from local potentials aiming at a microscopic understanding of scattering processes by impurities, phonons and barriers, relevant to (far-out of equilibrium) quantum spin transport. Additionally, we address the theoretical question, "how does a quantum many-body topological excitation scatters from a potential?" This question is also relevant in other systems with topological excitations of actual experimental and theoretical interest. Moreover, we study the thermodynamics of the aforementioned system, where aiming at a physical picture of the (thermo-) dynamics, we look at the low energy dispersions of the underlying string excitations where we find that they are simple expressions in terms of dressed momenta which however are temperature dependent. By reformulating the expressions of the specific heat and magnetic susceptibility we point out that, in contrast to field theoretic approaches, completely different string excitations correspondingly contribute. On the relaxation functions, a very interesting recent extension of TBA was proposed for space-time dependent densities under the name of Generalized Hydrodynamics approach (GHD). Using the GHD approach in the linear approximation, we analyze the relaxation of wavevector-q dependent thermal/magnetization profiles. As a byproduct we obtain the Drude weights as integrals over frequency of the wavector-q relaxation spectral function, of course closely related to linear response conductivities. This study provides theoretical background to present and feature experiments in 1D quantum magnets , e.g dynamic heat transport and transient grating spectroscopy experiments , that probe the relaxation of magnetization/thermal density profiles.

Language

English

Subject

Quantum integrability

Quantum magnetism

Strongly correlated systems

Topological quantum many body excitations

Ισχυρά συζευγμένα συστήματα

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