Phases and Phase Transitions in Quantum Ferromagnets
In this dissertation we study the phases and phase transition properties of quantum ferromagnets and related magnetic materials. We first investigate the effects of an external magnetic field on the Goldstone mode of a helical magnet, such as MnSi. The field introduces a qualitatively new term in...
Main Author: | |
---|---|
Other Authors: | |
Language: | en_US |
Published: |
University of Oregon
2015
|
Subjects: | |
Online Access: | http://hdl.handle.net/1794/18716 |
id |
ndltd-uoregon.edu-oai-scholarsbank.uoregon.edu-1794-18716 |
---|---|
record_format |
oai_dc |
spelling |
ndltd-uoregon.edu-oai-scholarsbank.uoregon.edu-1794-187162019-03-22T05:10:34Z Phases and Phase Transitions in Quantum Ferromagnets Sang, Yan Deutsch, Miriam Quantum ferromagnets Quantum phase transitions In this dissertation we study the phases and phase transition properties of quantum ferromagnets and related magnetic materials. We first investigate the effects of an external magnetic field on the Goldstone mode of a helical magnet, such as MnSi. The field introduces a qualitatively new term into the dispersion relation of the Goldstone mode, which in turn changes the temperature dependences of the contributions of the Goldstone mode to thermodynamic and transport properties. We then study how the phase transition properties of quantum ferromagnets evolve with increasing quenched disorder. We find that there are three distinct regimes for different amounts of disorder. When the disorder is small enough, the quantum ferromagnetic phase transitions is generically of first order. If the disorder is in an intermediate region, the ferromagnetic phase transition is of second order and effectively characterized by mean-field critical exponents. If the disorder is strong enough the ferromagnetic phase transitions are continuous and are characterized by non-mean-field critical exponents. 2015-01-14T15:57:05Z 2015-01-14T15:57:05Z 2015-01-14 Electronic Thesis or Dissertation http://hdl.handle.net/1794/18716 en_US All Rights Reserved. University of Oregon |
collection |
NDLTD |
language |
en_US |
sources |
NDLTD |
topic |
Quantum ferromagnets Quantum phase transitions |
spellingShingle |
Quantum ferromagnets Quantum phase transitions Sang, Yan Phases and Phase Transitions in Quantum Ferromagnets |
description |
In this dissertation we study the phases and phase transition properties of
quantum ferromagnets and related magnetic materials. We first investigate the effects of an external magnetic field on the Goldstone mode of a helical magnet, such as MnSi. The field introduces a qualitatively new term into the dispersion relation of the Goldstone mode, which in turn changes the temperature dependences of the contributions of the Goldstone mode to thermodynamic and transport properties. We then study how the phase transition properties of quantum ferromagnets evolve with increasing quenched disorder. We find that there are three distinct regimes for different amounts of disorder. When the disorder is small enough, the quantum ferromagnetic phase transitions is generically of first order. If the disorder is in an intermediate region, the ferromagnetic phase transition is of second order and effectively characterized by mean-field critical exponents. If the disorder is strong enough the ferromagnetic phase transitions are continuous and are characterized by non-mean-field critical exponents. |
author2 |
Deutsch, Miriam |
author_facet |
Deutsch, Miriam Sang, Yan |
author |
Sang, Yan |
author_sort |
Sang, Yan |
title |
Phases and Phase Transitions in Quantum Ferromagnets |
title_short |
Phases and Phase Transitions in Quantum Ferromagnets |
title_full |
Phases and Phase Transitions in Quantum Ferromagnets |
title_fullStr |
Phases and Phase Transitions in Quantum Ferromagnets |
title_full_unstemmed |
Phases and Phase Transitions in Quantum Ferromagnets |
title_sort |
phases and phase transitions in quantum ferromagnets |
publisher |
University of Oregon |
publishDate |
2015 |
url |
http://hdl.handle.net/1794/18716 |
work_keys_str_mv |
AT sangyan phasesandphasetransitionsinquantumferromagnets |
_version_ |
1719005399859855360 |