B位调控钙钛矿钴氧化物的CMR效应及自旋态研究

项目名称： B位调控钙钛矿钴氧化物的CMR效应及自旋态研究

项目编号： No.61201119

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 电子学与信息系统

项目作者： 毋志民

作者单位： 重庆师范大学

项目金额： 25万元

中文摘要： 钙钛矿结构钴氧化物因具有庞磁电阻效应，在提高磁存贮密度及制备磁敏感探测元件上具有广阔的应用前景，同时这类材料还存在着自旋、电荷、晶格和轨道之间的耦合，表现出自旋态转变、自旋玻璃态、相分离等丰富的物理内容，涉及到自旋电子学的许多基本问题，具有重要的学术意义。本项目主要研究B位调控对钙钛矿结构钴氧化的CMR效应和钴离子自旋态的影响。利用代表三种不同作用的Cr，In，Ga离子替代部分Co离子，分别研究新的磁相互作用、晶格失配和磁性离子稀释对钙钛矿钴氧化物性能的影响。找到具有最大CMR效应的最佳掺杂元素和最优掺杂点，利用电磁测量和基于LSDA+Hubbard U的第一性原理计算相结合的手段，详细研究其钴离子自旋态转变及自旋玻璃态等相关物性，探索出能够有效确定Co离子自旋态及其转变的方法，对理解这类强关联体系具有CMR效应的内在机理，制备出性能稳定的高密度磁存贮元件和磁敏感探测器件都具有深远的意义。

中文关键词： 钙钛矿钴氧化物；B位掺杂；CMR效应；钴离子自旋态；磁结构

英文摘要： The discovery of colossal magnetoresistance effect (CMR) in perovskite cobaltite oxide has sparked considerable renewed interests with an eye towards both on understanding of the CMR and related properties and potential applications in magnetic information store and low-field magnetic sensors. These materials also exhibit intriguing physical properties such as spin state transition, spin glass, phase separation, and so on, because of coexistence of and competition between spin, charge, lattice and obitail coupling. The full understanding of these properties will definitely stimulated the progress of spintronics. In this work, we mainly study B-site doping on CMR effect and Co ions'spin state transiton.Some of Co ions will be substituted by Cr, In, or Ga ions which represent three kinds of interaction, and the effect of new magnetic interaction, lattice distortion and dilute of magnetic ions on the physical properties of perovskite cobaltites will be studied respectively. The best doping element and optimal concentration will be investigated to find the maximum CMR effect. First principles calculation based on the LSDA + Hubbard U and combination with electromagnetic measurements will be used to carefully study Co ions' spin state transition and spin glass behaiviour to effectively determine the spin state of Co

英文关键词： perovskite cobaltites；B site doping;；CMR effect；Co ion’s spin state；magnetic structure