本文選題：鈣鈦礦　切入點：層狀鈣鈦礦　出處：《中國科學技術大學》2017年博士論文

【摘要】：鈣鈦礦氧化物的研究一直是材料科學和凝聚態(tài)物理研究的前沿領域之一。上世紀中葉,鈦酸鉛、鈦酸鋇等材料以其優(yōu)越的壓電、鐵電性質以及實用性受到了科研工作者的關注。八十年代銅氧化合物高溫超導體,提升了人們對這類材料研究的熱情。自旋電子學器件及信息存儲等領域的高速發(fā)展,激發(fā)了人們對磁性氧化物進一步的興趣,尤其是在鈣鈦礦或層狀鈣鈦礦結構氧化物中。同時,鈣鈦礦及層狀鈣鈦礦氧化物中的復雜相互作用使其不僅具有豐富的物理性質,還表現(xiàn)出良好的應用前景。探索高質量單晶薄膜的制備,是研究內在物理機制及宏觀表現(xiàn)的基礎,也是原型器件制備乃至下一步工業(yè)化應用的前提。而更好的理解材料中晶格、電荷、自旋與軌道等多種自由度之間的相互作用是探索磁性氧化物內在機理的基本途徑,更是將磁性氧化物推向應用的不可或缺的一部分。本文涉及的研究內容,按照研究材料的結構類型可以分為兩部分,即簡單鈣鈦礦磁性氧化物和復雜層狀鈣鈦礦磁性氧化物。第一部分研究是基于簡單鈣鈦礦結構的新型磁性氧化物研究,側重于高質量可控制備薄膜中多自由度耦合機理的研究,并嘗試進行調控;第二部分是在第一部分基礎上,針對更加復雜的大周期層狀鈣鈦礦結構氧化物的磁性及多鐵性研究,在制備單晶外延薄膜的基礎上,從周期數(shù)目和摻雜兩種角度出發(fā),研究薄膜磁性及多鐵性表現(xiàn)并探討其深層物理機制。本論文第一章是文獻綜述,主要介紹鈣鈦礦結構的基本特點和磁性相互作用的類型,初步介紹了文獻中已有磁性氧化物和多鐵磁電耦合材料的基本情況,分別回顧總結了簡單鈣鈦礦結構的LaCo03應力薄膜及復雜層狀鈣鈦礦結構的Aurivilliu相多鐵磁電材料的研究進展,確定了本論文的研究方向。第二章是論文研究過程中使用的試驗技術總結介紹,其中包括薄膜制備,形貌結構、宏觀物性、電子結構等表征分析,與微納器件的加工制造等。第三章是基于簡單鈣鈦礦結構新型磁性氧化物LaCo03薄膜的研究,重點在于關注多自由度耦合機制的表現(xiàn)和調控�；诹己迷优_階的單一截止面襯底及原位反射式高能電子衍射監(jiān)控手段,制備了大量不同類型的對比樣品,系統(tǒng)研究應力與缺陷共同作用于薄膜鐵磁性的機制,發(fā)現(xiàn)了一種高溫高對稱材料體系中的本征鐵磁絕緣體,對于自旋電子學器件的發(fā)展具有重大意義。同時,詳細地探索了薄膜的晶體結構、表面形貌、磁疇圖案、磁性(動力學)、導電性、光學等隨厚度的變化規(guī)律,以及通過厚度控制實現(xiàn)結構疇對薄膜磁疇及磁各向異性的調控。最后在LaCo03/LaA103//SrTi03雙層薄膜樣品中,依據(jù)宏觀磁性的調控結果,借助同步輻射半指數(shù)峰衍射、掃描透射電子顯微學以及軟X射線吸收譜學等分析手段,更加深刻地理解了應力、電荷以及氧八面體旋轉等多種自由度在界面處的耦合作用。第四章是關于層狀復雜鈣鈦礦結構材料外延薄膜的制備與表征研究。內容主要分成兩個部分:其一,基于結構周期物性調制思路,通過制備文獻尚未報道的具有超大周期結構的Bi11(Fe5CoTi3)10/9O33薄膜,探索超大周期結構的薄膜制備及其磁電性能,研究發(fā)現(xiàn)薄膜內部存在一種自調制的結構形式,同時在室溫同樣具有鐵電鐵磁性;其二,基于元素摻雜調控思路,研究精準摻雜條件下Aurivillius多鐵薄膜結構和物性的系統(tǒng)變化。發(fā)現(xiàn)摻雜濃度存在臨界數(shù)值大小,且對薄膜晶體結構、電子結構的影響很大,低摻雜的薄膜多鐵性有一定的增強,摻雜對物性的調控作用比較明顯。最后,第五章是對全文內容的總結,創(chuàng)新點提煉以及對未來工作的展望。
[Abstract]:Study on perovskite oxide is one of the materials science and research frontier in condensed matter physics. The middle of the last century, lead titanate, barium titanate and other materials with excellent piezoelectric, ferroelectric properties and practicability by scientific researchers. In 80s the cuprate superconductors, enhance the enthusiasm for this kind of material study on the rapid development of spintronic devices and information storage and other fields, it inspires people to further magnetic oxides, especially in perovskite or layered perovskite oxides. At the same time, the complex interaction of calcium titanium ore and layered perovskite oxides in which not only has rich physical properties, but also show the application prospect good. To explore the high quality single crystal films, is based on the intrinsic physical mechanism and macro performance, is prepared and a prototype device The premise of step industrial application. And the lattice, a better understanding of the material in charge, spin and orbital interactions between the various degrees of freedom is a basic way to explore the internal mechanism of magnetic oxide, is an integral part of the magnetic oxide to the application. The research content of this paper and the related research materials, according to the type of structure can be is divided into two parts, namely simple perovskite oxides and complex magnetic layered perovskite magnetic oxides. The first part is a study of novel magnetic oxide simple perovskite structure based on the research focus on the high quality control of multi degree of freedom coupling mechanism of preparation of films, and try to control; the second part is on the basis of the first part, according to the study magnetic cycle more complex layered perovskite oxides and multiferroic, based on epitaxial thin film preparation, from the number of cycles And doped with two kinds of point of view, research and multiferroic thin film magnetic performance and explore the underlying physical mechanism. The first chapter is the literature review, the basic characteristics and types of magnetic perovskite structure mainly introduces the interaction, initially introduced the basic situation of coupled magnetic oxide materials of the existing literature and magnetoelectric. Were reviewed and summarized the simple perovskite structure LaCo03 progress in research on stress film and complex layered perovskite Aurivilliu phase multiferroic magnetoelectric materials, determine the research direction of this thesis. The second chapter is the study of test process using summaries, including film preparation, morphology and macroscopic properties. Analysis of the electronic structure, and micro nano device manufacturing. The third chapter is the research on new magnetic oxide LaCo03 films simple perovskite structure based on the focus is off Performance and mechanism of coupling injection of multiple degrees of freedom. A single atomic step of substrate surface as well and in situ reflection high energy electron diffraction monitoring method based on a large number of different types of sample preparation system of the common action of stress and defects in ferromagnetic thin film system, found the intrinsic ferromagnetic insulator high temperature high symmetry material system, is of great significance to the development of spintronics devices. At the same time, explored the film crystal structure, surface morphology, magnetic domain pattern (kinetics), conductivity, optical variations with the thickness, and thickness of the control regulation of the thin film magnetic domain structure domain and the magnetic anisotropy. Finally LaCo03/LaA103//SrTi03 bilayer thin film samples, based on the result of regulation on magnetic properties, using synchrotron radiation diffraction peak half index, scanning transmission electron microscopy to And the soft X ray absorption spectroscopy and other analytical methods, a more profound understanding of the stress, charge and oxygen in eight face rotation and other degrees of freedom at the interface coupling. The fourth chapter is the research on the synthesis and characterization of layered complex perovskite epitaxial films. The main content is divided into two parts: a structure of ideas based on the modulation cycle, making literature had not been reported with a large periodic structure by Bi11 (Fe5CoTi3) 10/9O33 films, explore the superperiod structure preparation and magnetoelectric properties of thin films, the study found that the presence of a self modulated structure within the thin films, but also is the ferroelectric ferromagnetic at room temperature; second based on the ideas of doping, regulation, system changes Aurivillius multiferroic thin film structure and properties of precise doping conditions. It is found that the doping concentration is the critical numerical value, and the crystal structure of the films, The influence of electronic structure is very large. The ferromagnetic properties of low doped films are enhanced. The regulation effect of dopants on physical properties is obvious. The fifth chapter is the summary of the full text, the innovation and the prospect for future work.

【學位授予單位】：中國科學技術大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TQ133.3;TB383.2
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本文編號：1691234