Exploring Phase Separation in Manganite Films

技术摘要为了了解在锰氧化物中观察到的相共存的起源和性质，本项目将在应变和压力下测量多个长度尺度上的锰氧化物薄膜的磁性、电子和结构性质。高分辨率的X射线衍射测量将被用来确定薄膜组分和衬底的晶格参数。同时，还将确定过渡金属原子和氧原子的局域结构和价态。除了整体磁化测量外，还将通过光激电子发射显微镜(PEEM)测量对表面进行详细的磁成像。将对图案化的薄膜进行检查，以探索几何效应。薄膜的结果将与平行磁化和高压输运以及相应大块样品的结构测量结果进行比较。通过这种方法，我们将能够区分外在效应和本征效应，以及探索与块状样品相比在锰氧化物表面的变化。研究生和本科生将参与这项工作的所有层面，包括样品制备、实验室和基于同步加速器的测量、建模和数据分析。为纽瓦克地区高中生设计的为期七周的过渡金属氧化物制备和表征暑期研究和教学计划将继续进行，并将扩大到为高中教师举办为期两周的研讨会，使他们能够将该计划的组成部分实施到他们的实验室实验中。非技术摘要锰氧化物在压力、磁场、光和电场的响应下表现出显著的电导率变化。由于这种敏感性，这些材料在开发新的磁性传感器和非易失性数据存储方面显示出很大的前景。然而，为了真正了解对外部刺激的反应的来源并将其优化应用，还需要进行大量的基础研究。了解相共存是所需基础研究的中心部分。该项目将在应变和压力下测量多个长度尺度上的锰氧化物薄膜的磁性、电学和结构特性，以全面表征对外部扰动的响应。基于同步加速器的X射线方法将被用来确定结构、价态和磁性。结果将导致这些材料的更详细的模型，并可能在应用中优化它们的方法。研究生和本科生将参与这项工作的所有层面，包括样品制备、实验室和基于同步加速器的测量、建模和数据分析。为纽瓦克地区高中生设计的为期七周的过渡金属氧化物制备和表征暑期研究和教学计划将继续进行，并将扩大到为高中教师举办为期两周的研讨会，使他们能够将该计划的组成部分实施到他们的实验室实验中。该计划将整合到高中科学实验室课程中。这将有助于(1)培养科学素养，并直接影响学生从事科学事业，(2)向高中教师和高中生以及其他无法使用现代研究设施的人提供接触实验技术和方法的机会。

Technical Abstract In order to understand the origin and properties of the observed phase coexistence in manganites, this project will measure the magnetic, electronic and structural properties of manganite films on multiple length scales under strain and under pressure. High resolution x-ray diffraction measurements will be applied to determine the lattice parameters of the film components and the substrates. In parallel, the local structure and valence about the transition metal atoms and the oxygen atoms will be determine. In addition to bulk magnetization measurements, detailed magnetic imaging of the surface will be conducted by photoexcitation electron emission microscopy (PEEM) measurements. Patterned films will be examined to explore geometrical effect. The film results will be compared with parallel magnetization and high pressure transport and structural measurements on the corresponding bulk samples. In this way, we will be able to separate extrinsic effects from intrinsic effect as well to explore changes at the surface of manganites in comparison with bulk samples. Graduate and undergraduate students will be involved in all levels of this work including sample preparation, laboratory and synchrotron based measurements, modeling and data analysis. A seven week summer research and teaching program on transition metal oxide preparation and characterization, designed for Newark area high school students will be continued and expanded to include a two-week workshop for high school teachers to enable them to implement components of the program into their laboratory experiments. Non-Technical Abstract Manganite oxides exhibit significant changes in electrical conductivity in response to pressure, magnetic fields, light, and electrical fields. As a result of this sensitivity, these materials show much promise for the development of new magnetic sensors and non-volatile data storage. However, much basic research is needed in order to truly understand the origin of the response to external stimuli and to optimizer them for applications. Understanding phase coexistence is a central part of the required basic research. This project will measure the magnetic, electronic and structural properties of manganite films on multiple length scales under strain and under pressure to fully characterize the response to external perturbations. Synchrotron based x-ray methods will be used to determine the structure, valence and magnetic properties. The results will lead to more detailed models of these materials, and possibly, methods for optimizing them in applications. Graduate and undergraduate students will be involved in all levels of this work including sample preparation, laboratory and synchrotron based measurements, modeling and data analysis. A seven week summer research and teaching program on transition metal oxide preparation and characterization, designed for Newark area high school students will be continued and expanded to include a two-week workshop for high school teachers to enable them to implement components of the program into their laboratory experiments. The program will be integrated into high school science laboratory courses. This will serve to (1) develop scientific literacy and to directly influence students to pursue careers in science, and (2) provide exposure to experimental techniques and methods to high school teachers and high school students and to others who do not have access to modern research facilities.