{"created":"2023-06-20T13:20:38.133205+00:00","id":674,"links":{},"metadata":{"_buckets":{"deposit":"67d8fda1-b282-41dc-a8d1-d611e66bee5b"},"_deposit":{"created_by":1,"id":"674","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"674"},"status":"published"},"_oai":{"id":"oai:ir.soken.ac.jp:00000674","sets":["2:428:15"]},"author_link":["0","0","0"],"item_1_creator_2":{"attribute_name":"著者名","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"邱, 宇"}],"nameIdentifiers":[{"nameIdentifier":"0","nameIdentifierScheme":"WEKO"}]}]},"item_1_creator_3":{"attribute_name":"フリガナ","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"クイユ"}],"nameIdentifiers":[{"nameIdentifier":"0","nameIdentifierScheme":"WEKO"}]}]},"item_1_date_granted_11":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2006-09-29"}]},"item_1_degree_grantor_5":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"総合研究大学院大学"}]}]},"item_1_degree_name_6":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士（理学）"}]},"item_1_description_12":{"attribute_name":"要旨","attribute_value_mlt":[{"subitem_description":" Since some 3D type perovkite compounds have been found in the experiments to
give gigantic dielectric constant, in contrast to the ordinary dielectrics, its
underlying microscopic mechanism has attractted much attention in the field of
solid state theory. As is well-known, the ferroelectric modes play an important roll
in the dielectric property, transportation and phase transition or these materials.
Many efforts were already performed on the connection of this ferroelectric mode
with the quartic or sextic anharmonic oscillators. ln experiment, glgantic
photo-enhancements of the electronic conductivity and the dielectric constant have
recently been observed in SrTiO3. lt was also pointed out that, this dielectric
enhancement remains to exist only under the ultraviolet (UV) illumination, while
vanishes as the illumination is turned off. As for the photo-induced electronic
conduction in SrTiO3, it is expected to be an alternative mechanism from that of the
ordinary field induced one in metallic systems. However, the microscopic origin of
these photo-induced phenomena has not yet been clarified theoretically. Thus, this
is just the motivation of the present study.
We will give a short introduction to the soft mode theory in the
second chapter since our work will be mainly based on this theory.
The spatial structure and the electronic property of this 3D
perovskite. SrTi03, are also stated. since we will focus our efforts
only on this compound in the present work. Some key points of the
previous studies on the fundamental properties of SrTiO3, are
summerized as well. =n Chapter 3, a detailed illustration is given
to the Super-Para-Electric (SPE) large polarons, from the set-up of
the cheoretic model to the numerical calculatlons, and ends up with
the impurity effect on this polaron. Combining the experimentally
observed dielectrlc and conductive properties with previous
theoretical researches on the model for this crystal, we give a further
investigation into the model and come up with a new model for the
photo excited state of the crystal. By which, we can adiabatically
obtain the corresponding energy surface and find all the metastable
states on it. With the investigation of each of such states, We can
find its connection with the dielectric and conductive property of
this crystal･ We also give an investigation into the most stable
quasiparticle state for the many electron system within the adeabatic
method and give a description to the possible lattice configurations
for the photo excited state of the electron and phonon coupling system.
Then it is followed by Chapter 4, the appllcations of this SPE polaron
theory in the interpretation of the photo-induced giant dielectric
constant and electronic conductivity. We will first discuss one of
the fundamental problems for phonons, phonon softening or phonon
hardening with the introduction of e-p coupling. Then we will apply
our SPE large polaron theory to the experimentally observed static
dielectric enhancement in srTiO3, clarifying the microscopic origin
of this photo-induced phase transition. In the following, we will
give a phenomenological interpretation to the experimentally reported
metallic conduction in SrTiO3 by studying the translational property
of the polarons. In Chapter 5, we will discuss the relaxation process
of the lattice after the photo-excitation. It has already been studied
that for polymers, the formation of the polaron or exciton is an
ultra-fast process. [6l] In experiment, these states could be detected
and predicted from the spectra. However, by virtue of the molecular
dynamics theory, the information of the lattice configuration as well
as the electronic state can be traced so as to compare with the
energetic evolution. Then, the lattice relaxation process could be
recognized more clearly. We will first give a deschption to the
molecular dynamics theory for the e-p interacting system. Then, we
will apply this method to SrTiO3 and give some detailed descriptions
about the relaxation process in this crystal. We will show the
formation of the SPE large polaron is an ultra-fast process of about
several picoseconds, and how the electron and phonon interaction
system releases its energy so as to reach its new stable state. The
influence of the electron and phonon interaction strength and the
size of the electron and phonon coupling system on the relaxation
process will be shown. A summary of all the conclusions of these
studies is given at Chapter 6.","subitem_description_type":"Other"}]},"item_1_description_7":{"attribute_name":"学位記番号","attribute_value_mlt":[{"subitem_description":"総研大甲第989号","subitem_description_type":"Other"}]},"item_1_select_14":{"attribute_name":"所蔵","attribute_value_mlt":[{"subitem_select_item":"有"}]},"item_1_select_8":{"attribute_name":"研究科","attribute_value_mlt":[{"subitem_select_item":"高エネルギー加速器科学研究科"}]},"item_1_select_9":{"attribute_name":"専攻","attribute_value_mlt":[{"subitem_select_item":"13 物質構造科学専攻"}]},"item_1_text_10":{"attribute_name":"学位授与年度","attribute_value_mlt":[{"subitem_text_value":"2006"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"QIU, Yu","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"0","nameIdentifierScheme":"WEKO"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲989_要旨.pdf","filesize":[{"value":"265.9 kB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"要旨・審査要旨","url":"https://ir.soken.ac.jp/record/674/files/甲989_要旨.pdf"},"version_id":"4542bfbc-ae83-4a24-b6a8-58f50a69a08f"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲989_本文.pdf","filesize":[{"value":"4.9 MB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"本文","url":"https://ir.soken.ac.jp/record/674/files/甲989_本文.pdf"},"version_id":"936fb837-dafc-4109-b8b8-33a704a4ca80"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"thesis","resourceuri":"http://purl.org/coar/resource_type/c_46ec"}]},"item_title":"Dual Electron-phonon Coupling Model for Giant Photoenhancements of Dielectric Constant and Electronic Conductivity in SrTiO3","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Dual Electron-phonon Coupling Model for Giant Photoenhancements of Dielectric Constant and Electronic Conductivity in SrTiO3"},{"subitem_title":"Dual Electron-phonon Coupling Model for Giant Photoenhancements of Dielectric Constant and Electronic Conductivity in SrTiO3","subitem_title_language":"en"}]},"item_type_id":"1","owner":"1","path":["15"],"pubdate":{"attribute_name":"公開日","attribute_value":"2010-02-22"},"publish_date":"2010-02-22","publish_status":"0","recid":"674","relation_version_is_last":true,"title":["Dual Electron-phonon Coupling Model for Giant Photoenhancements of Dielectric Constant and Electronic Conductivity in SrTiO3"],"weko_creator_id":"1","weko_shared_id":1},"updated":"2023-06-20T16:00:13.643972+00:00"}