|
Identifier |
000390009 |
Title |
Dynamics of field-induced phases in spin-1 antifferomagnetic chains |
Alternative Title |
Δυναμική μαγνητικού πεδίου επαγώμενων φάσεων σε S=1 αντισιδηρομαγνητικές αλυσίδες |
Author
|
Ψαρουδάκη, Χριστίνα
|
Thesis advisor
|
Ζώτος, Ξενοφών
Παπανικολάου, Νικόλαος
|
Abstract |
This thesis is devoted to the study of a class of antifferomagnetic spin-1 chains
with a strong easy plane anisotropy in the presence of magnetic field. At zero
temperature the system undergoes two quantum phase transitions at critical
fields. Reliable and detailed theoretical analysis is provided on the Electron
Spin Resonance (ESR) spectrum, thermodynamics and the thermal transport of
the model. The tools at hand range from exact analytical solutions and to
numerical simulation techniques. The S=1 antiferromagnet in a magnetic field
can be systematically mapped onto an S=1/2 ΧΧΖ chain in a longitudinal
magnetic field. This effective S=1/2 description has been extensively used in
order to gain a better physical understanding of the original S=1 chain.
For the Electron Spin Resonance spectrum, apart from the theoretical analysis,
high-field ESR experimental studies of the compound NiCl2 - 4SC(NH22)22
(abbreviated as DTN) are presented and found consistent with theoretical
predictions. The most interesting feature is the experimental signature of the
single-ion two-magnon bound state.
Part of this thesis is devoted to the magnetic-field and temperature dependence
of magnetization and specific heat for the whole field-region and a wide range
of temperatures, with special emphasis at the critical behaviour of these
quantities at the critical fields. Finally, the calculation of dynamic correlation
functions pertinent to the study of thermal transport is addressed for the S=1
model with easy plane anisotropy and the S=1/2 XXZ model in the presence of
finite magnetic field.
|
Language |
English |
Subject |
Electron spin resonance |
|
Quantum magnetism |
|
Spin chains |
|
Thermal transport |
|
Αλυσίδες σπιν |
|
Κβαντικός μαγνητισμός |
Issue date |
2014-12-22 |
Collection
|
School/Department--School of Sciences and Engineering--Department of Physics--Doctoral theses
|
|
Type of Work--Doctoral theses
|
Views |
734 |