钙钛矿锰氧化物的光电磁调控及应力效应-光学工程专业论文.docxVIP

Master Dissertation of Suzhou University of Science and Technology Strain effect and field modification in epitaxial thin films of perovskite manganite Master Candidate: Yuanyuan Yang Supervisor: Prof.Ju Gao Major: Optical Engineering Suzhou University of Science and Technology School of Mathematics and Physics June, 2015 学位 学位论文答辩委员会名单 I I 苏州科技学院硕士论文 摘 要 摘 要 钙钛矿锰氧化物具有极为丰富的新奇物理现象，如庞磁阻效应（CMR）、电 荷/轨道有序、相分离及 Mott 转变等等，是目前物理和材料领域研究的热点。锰 氧化物中各量子态具有相近的自由能，造成多个亚稳相的共存与竞争，因此锰氧 化物对外加物理场（如磁、光、电、应力等）极为敏感。本论文中，以钙钛矿锰 氧化物典型材料 La0.7Sr0.3MnO3（LSMO）为研究对象，探索它的光电磁特性以及 应力效应下的电输运特性。具体内容如下： 1、采用脉冲激光沉积的方法优化薄膜的制备工艺，在 LaAlO3（LAO）(001)衬底 上制备出高质量的 LSMO 薄膜。 2、研究 LSMO/LAO 薄膜的电、磁输运特性以及光电导效应。发现在测量温度 范围内（50 K~400 K），LSMO/LAO 薄膜的金属-绝缘体转变不明显且居里温 度 Tc 很高，同时观察到负磁阻效应和正光电导效应。 3、在 SrTiO3（STO）、（La, Sr）（Al, Ta）O3（LSAT）以及 LaAlO3（LAO）单晶 衬底外延生长出高质量的 LSMO 薄膜，研究衬底引入的晶格应变对 LSMO 薄 膜的电性调控、磁性调控以及光致电阻调控的影响。研究发现应力的引入会 降低材料的居里温度 Tc，并且影响材料的电、磁输运特性。 关键词：钙钛矿锰氧化物，场调控，强关联电子体系，亚稳相 苏州科技学院硕士论文Abs 苏州科技学院硕士论文 Abstract II II Abstract Perovskite manganite have received a great deal of interest in physics and material science because of a variety of interesting properties such as colossal magnetoresistance (CMR), charge/orbital ordering, phase separation, Mott transition and so on. The preovksite manganites are at the quantum phase boundary and their novel behaviors are associated with the coexistence and competition of quantum states, which are sensitive to the external fields including magnetic field, electrical field, light and strain. In this dissertation, La0.7Sr0.3MnO3（LSMO）films are chosen to study their photoconductivity, electrical property, magnetical property under strain. The main contents and research results are concluded as follows: High-quality epitaxial LSMO films have been grown directly on LaAlO3（LAO） substrate by pulsed laser deposition using optimized the deposition conditions. The electric-magnetic transport properties and photoinduced effect have been studied. The metal-insulator transition was not o