{"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<br />give gigantic dielectric constant, in contrast to the ordinary dielectrics, its<br />underlying microscopic mechanism has attractted much attention in the field of<br />solid state theory. As is well-known, the ferroelectric modes play an important roll<br />in the dielectric property, transportation and phase transition or these materials.<br />Many efforts were already performed on the connection of this ferroelectric mode<br />with the quartic or sextic anharmonic oscillators. ln experiment, glgantic<br />photo-enhancements of the electronic conductivity and the dielectric constant have<br />recently been observed in SrTiO3. lt was also pointed out that, this dielectric<br />enhancement remains to exist only under the ultraviolet (UV) illumination, while<br />vanishes as the illumination is turned off. As for the photo-induced electronic<br />conduction in SrTiO<sub>3</sub>, it is expected to be an alternative mechanism from that of the<br />ordinary field induced one in metallic systems. However, the microscopic origin of<br />these photo-induced phenomena has not yet been clarified theoretically. Thus, this<br />is just the motivation of the present study.<br />　We will give a short introduction to the soft mode theory in the<br />second chapter since our work will be mainly based on this theory.<br />The spatial structure and the electronic property of this　3D<br />perovskite. SrTi0<sub>3</sub>, are also stated. since we will focus our efforts<br />only on this compound in the present work. Some key points of the<br />previous studies on　the fundamental properties of SrTiO<sub>3</sub>, are<br />summerized as well. =n Chapter 3, a detailed illustration is given<br />to the Super-Para-Electric (SPE) large polarons, from the set-up of<br />the cheoretic model to the numerical calculatlons, and ends up with<br />the impurity effect on this polaron. Combining the experimentally<br />observed dielectrlc and conductive properties with previous<br />theoretical researches on the model for this crystal, we give a further<br />investigation into the model and come up with a new model for the<br />photo excited state of the crystal.  By which, we can adiabatically<br />obtain the corresponding energy surface and find all the metastable<br />states on it. With the investigation of each of such states,　We can<br />find its connection with the dielectric and conductive property of<br />this crystal･ We also give an investigation into the most stable<br />quasiparticle state for the many electron system within the adeabatic<br />method and give a description to the possible lattice configurations<br />for the photo excited state of the electron and phonon coupling system.<br />Then it is followed by Chapter 4, the appllcations of this SPE polaron<br />theory in the interpretation of the photo-induced giant dielectric<br />constant and electronic conductivity. We will first discuss one of<br />the fundamental problems for phonons, phonon softening or phonon<br />hardening with the introduction of e-p coupling. Then we will apply<br />our SPE large polaron theory to the experimentally observed static<br />dielectric enhancement in srTiO<sub>3</sub>, clarifying the microscopic origin <br />of this photo-induced phase transition. In the following, we will<br />give a phenomenological interpretation to the experimentally reported<br />metallic conduction in SrTiO<sub>3</sub> by studying the translational property<br />of the polarons. In Chapter 5, we will discuss the relaxation process<br />of the lattice after the photo-excitation. It has already been studied<br />that for polymers, the formation of the polaron or exciton is an<br />ultra-fast process. <sup>[6l]</sup> In experiment, these states could be detected<br />and predicted from the spectra. However, by virtue of the molecular<br />dynamics theory, the information of the lattice configuration as well<br />as the electronic state can be traced so as to compare with the<br />energetic evolution. Then, the lattice relaxation process could be<br />recognized more clearly. We will first give a deschption to the <br />molecular dynamics theory for the e-p interacting system. Then, we<br />will apply this method to SrTiO<sub>3</sub> and give some detailed descriptions<br />about the relaxation process in this crystal. We will show the<br />formation of the SPE large polaron is an ultra-fast process of about<br />several picoseconds,　and how the electron and phonon interaction<br />system releases its energy so as to reach its new stable state. The<br />influence of the electron and phonon interaction strength and the<br />size of the electron and phonon coupling system on the relaxation<br />process will be shown. A summary of all the conclusions of　these<br />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"}