Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Theoretical developments in low-dimensional magnetic systems

Zhao, Zhen LU (2024)
Abstract
In this thesis, we investigate low-dimensional magnetic systems from the theoretical points of view. To address situations with several and distinct magnetic interactions, we develop different frameworks, including a magnon self-energy approach, a spin dynamical exchange-correlation (xc) field formalism and a scheme combining Matrix Product States method and exact diagonalization/nonequilibrium Green's function methods (MPS + ED/NEGF). By means of effective models, we study topics including magnetic frustration, homogeneous spin chain, magnetic skyrmions, and magnetic impurities.

The thesis is based on four papers: In Paper I, we apply the magnon self-energy approach to study the ground-state properties of two-dimensional... (More)
In this thesis, we investigate low-dimensional magnetic systems from the theoretical points of view. To address situations with several and distinct magnetic interactions, we develop different frameworks, including a magnon self-energy approach, a spin dynamical exchange-correlation (xc) field formalism and a scheme combining Matrix Product States method and exact diagonalization/nonequilibrium Green's function methods (MPS + ED/NEGF). By means of effective models, we study topics including magnetic frustration, homogeneous spin chain, magnetic skyrmions, and magnetic impurities.

The thesis is based on four papers: In Paper I, we apply the magnon self-energy approach to study the ground-state properties of two-dimensional Heisenberg models with competing exchange couplings. In Papers II and IV, the dynamical xc field formalism is used to calculate the Green's function. In Paper II, we propose a spin xc field formalism to calculate dynamical spin structure factor of the one-dimensional antiferromagnetic Heisenberg model at zero-temperature. In Paper IV, we investigate the Kondo spectral function by extending the xc field formalism to finite temperatures, and apply the formalism to the single-impurity Anderson model. In Paper III, we propose a MPS + ED/NEGF scheme to calculate the ground-state and dynamical properties of quantum magnetic skyrmions with itinerant electrons explicitly included. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Blügel, Stefan, Forschungszentrum Jülich (FZJ), Germany Peter Grünberg Institut (PGI) & Institute for Advanced Simulation (IAS) D-52425 Jülich, Germany.
organization
publishing date
type
Thesis
publication status
published
subject
keywords
magnetism, Heisenberg model, magnetic skyrmion, magnetic impurity, exact diagonalization, dynamical exchange-correlation field, MPS, NEGF, Kondo spectral function, Fysicumarkivet A:2024: Zhao
pages
176 pages
publisher
Department of Physics, Lund University
defense location
Rydberg Lecture Hall, Department of Physics, Lund University
defense date
2024-09-20 09:00:00
ISBN
978-91-8104-139-2
978-91-8104-140-8
language
English
LU publication?
yes
id
2db164d0-0d53-413a-9e9c-0bdd65d57474
date added to LUP
2024-08-13 15:55:34
date last changed
2024-08-27 15:53:45
@phdthesis{2db164d0-0d53-413a-9e9c-0bdd65d57474,
  abstract     = {{In this thesis, we investigate low-dimensional magnetic systems from the theoretical points of view. To address situations with several and distinct magnetic interactions, we develop different frameworks, including a magnon self-energy approach, a spin dynamical exchange-correlation (xc) field formalism and a scheme combining Matrix Product States method and exact diagonalization/nonequilibrium Green's function methods (MPS + ED/NEGF). By means of effective models, we study topics including magnetic frustration, homogeneous spin chain, magnetic skyrmions, and magnetic impurities.<br/><br/>The thesis is based on four papers: In Paper I, we apply the magnon self-energy approach to study the ground-state properties of two-dimensional Heisenberg models with competing exchange couplings. In Papers II and IV, the dynamical xc field formalism is used to calculate the Green's function. In Paper II, we propose a spin xc field formalism to calculate dynamical spin structure factor of the one-dimensional antiferromagnetic Heisenberg model at zero-temperature. In Paper IV, we investigate the Kondo spectral function by extending the xc field formalism to finite temperatures, and apply the formalism to the single-impurity Anderson model. In Paper III, we propose a MPS + ED/NEGF scheme to calculate the ground-state and dynamical properties of quantum magnetic skyrmions with itinerant electrons explicitly included.}},
  author       = {{Zhao, Zhen}},
  isbn         = {{978-91-8104-139-2}},
  keywords     = {{magnetism; Heisenberg model; magnetic skyrmion; magnetic impurity; exact diagonalization; dynamical exchange-correlation field; MPS; NEGF; Kondo spectral function; Fysicumarkivet A:2024: Zhao}},
  language     = {{eng}},
  publisher    = {{Department of Physics, Lund University}},
  school       = {{Lund University}},
  title        = {{Theoretical developments in low-dimensional magnetic systems}},
  url          = {{https://lup.lub.lu.se/search/files/193188733/e-nailing_ex_zhen.pdf}},
  year         = {{2024}},
}