Structure-Property Relationships in Colossal Magnetoresistance Thin Film Materials through Nanofabrication

本项目旨在通过纳米制造和表征来更好地理解一类铁磁性立方钙钛矿材料中的自旋、电荷和晶格耦合，该材料被称为巨磁电阻(CMR)材料。该项目还强调发展本科生和研究生的综合研究和教育机会。铁磁性立方钙钛矿材料如(La，Sr)MnO_3的磁阻响应对晶格应变非常敏感，从而对结构变形非常敏感。在揭示观察到的异常大磁阻效应的起源时，将结构扭曲与磁性和电学性质联系起来尤为重要。本项目主要研究(I)几何约束下的局域磁结构与应变状态之间的关系，以及(Ii)亚微米器件异质结中的磁输运问题。CMR材料的应变状态可以通过纳米加工的几何约束来定制，由此得到的纳米结构将被磁学和电子学表征。这种方法不仅提供了这些材料中异常大的磁阻背后的结构和磁学之间的相互作用的信息，而且还提供了随着磁性介质变得更致密而将它们结合到磁记录应用中的基本量子限制的信息。%该项目解决了具有高潜在技术相关性的材料科学的主题领域的基础研究问题。这项研究将在基础水平上为磁性设备的新方面贡献基本的材料科学知识。从研究中获得的基本知识和理解有望为改进材料和材料组合的设计和生产提供基本认识和基础，从而有助于提高先进器件的性能和稳定性。该计划的一个重要特点是通过在一个具有根本意义和技术意义的领域对学生进行培训，将研究和教育结合起来。

This project seeks greater understanding of the spin, charge and lattice coupling in a class of ferromagnetic cubic perovskite materials known as "colossal" magnetoresistance (CMR) materials through nanofabrication and characterization. The project also emphasizes the development of integrated research and educational opportunities at both the undergraduate and graduate levels. The magnetoresistive response of ferromagnetic cubic perovskite materials such as (La,Sr)MnO3 is extremely sensitive to lattice strain and thus to structural distortion. Correlating structural distortions with magnetic and electronic properties is particularly important in shedding light on the origin of the anomalously large magnetoresistance effect observed. This project specifically addresses (i) the relationship between local magnetic structure and the strain state through geometrical confinement and (ii) the magnetotransport in submicron size device heterostructures. The strain state of CMR materials can be tailored by geometrical confinement through nanofabrication and the resulting nanostructures will be characterized magnetically and electronically. This approach provides information not only on the interplay between structure and magnetics behind the anomalously large magnetoresistance in these materials but also on the fundamental quantum limit of their incorporation into magnetic recording applications as magnetic media become denser.%%%The project addresses basic research issues in a topical area of materials science having high potential technological relevance. The research will contribute basic materials science knowledge at a fundamental level to new aspects of magnetic devices. The basic knowledge and understanding gained from the research is expected to contribute to improving the perform-ance and stability of advanced devices by providing a fundamental understanding and a basis for designing and producing improved materials, and materials combinations. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area.***