MATERIALS WORLD NETWORK The Magnetostructural Response in Heterostructured Systems: a US - UK Collaboration

MATERIALS WORLD NETWORK 异质结构系统中的磁结构响应：美国 - 英国合作

基本信息

批准号：
EP/G065640/1
负责人：
Christopher Marrows
金额：
$ 63.82万
依托单位：
University of Leeds
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2009
资助国家：
英国
起止时间：
2009 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FG065640%2F1
关键词：
MATERIALS WORLD NETWORK Magnetostructural Response

项目摘要

Magnetic materials are ubiquitous in modern society, present in advanced devices, sensors and motors of every kind. As the magnetic force loses strength only over very long distances, it allows for communication between components that are physically well-separated. This unique property permits the conversion of electrical to mechanical energy, assists microwave devices in telecommunications, transmission and distribution of electric power, enables data storage systems and facilitates sensing of ambient conditions. Steady effort has been extended since the invention of the magnetic compass (first reported in the Qin Dynasty, 221 BC) to tailor and optimize magnetic materials' performance. Two thousand years later it is clear that breakthrough advances in the performance of magnetic devices will require new materials and novel design principles to control magnetic performance. In this project we will clarify the origins of a significant but poorly-understood phenomenon of extrinsic control of a classically intrinsic parameter - the magnetic transition temperature - in layered systems comprised of magnetic materials with strong electron-lattice coupling. This will be done by a joint transatlantic programme of research between the University of Leeds and STFC Rutherford Appleton Laboratory in the UK, and Northeastern University in the USA. Brookhaven National Laboratory will participate as a project partner. We shall use FeRh, which crystallizes in the CsCl phase, as a model system: this material undergoes a phase transition from antiferromagnetic (AF) to ferromagnetic (F) on warming through a critical temperature that is conveniently located at about 100 degrees Celsius, accompanied by an isotropic lattice expansion. As well as providing a material with the fascinating property that magnetism can be switched on and off at will, deep questions about the underlying mechanism for the transition remain.We have already demonstrated the capability to grow epitaxial thin films of this material in Leeds and the intrinsic transition has been characterized by SQUID, synchrotron x-ray diffraction, x-ray magnetic circular dichroism, and polarised neutron reflectometry by our research partners in the USA and UK. We now seek to use joint NSF-EPSRC support to cement this link, and carry out some novel experiments where we seek to control the AF-F phase transition using extrinsic parameters. In the films we have at present, as is known in the bulk, the position of the phase boundary can be controlled intrinsically by the exact FeRh stoichiometry. A few tantalising results are present in the literature where the transition has been quite markedly affected by other external parameters by building heterostructures incorporating magnetostructural materials. Here we will throw light on the underlying mechanism for the magnetostructural response by exploring such heterostructures and the response of the FeRh to extrinsic strain, magnetostatic and exchange fields, and seek ways in which they might be combined to enhance each other.

磁性材料在现代社会中无处不在，存在于各种先进设备、传感器和电机中。由于磁力仅在很长的距离内才会失去强度，因此它允许物理上分离的组件之间进行通信。这种独特的特性允许将电能转换为机械能，协助微波设备进行电信、电力传输和分配，支持数据存储系统并促进环境条件的感测。自磁罗盘发明（首次报道于公元前 221 年秦朝）以来，人们不断努力定制和优化磁性材料的性能。两千多年后，很明显，磁性器件性能的突破性进步将需要新材料和新颖的设计原理来控制磁性性能。在这个项目中，我们将阐明在由具有强电子晶格耦合的磁性材料组成的层状系统中，经典内在参数（磁转变温度）的外在控制现象的起源，这一现象是重要的，但人们对此知之甚少。这将由利兹大学和英国 STFC 卢瑟福阿普尔顿实验室以及美国东北大学之间的跨大西洋联合研究计划来完成。布鲁克海文国家实验室将作为项目合作伙伴参与。我们将使用在 CsCl 相中结晶的 FeRh 作为模型系统：这种材料在升温到临界温度（通常位于 100 摄氏度左右）时会经历从反铁磁 (AF) 到铁磁 (F) 的相变，同时伴随着通过各向同性晶格膨胀。除了提供一种具有磁性可以随意打开和关闭的迷人特性的材料外，关于转变的根本机制的深刻问题仍然存在。我们已经在利兹和英国展示了生长这种材料的外延薄膜的能力。我们在美国和英国的研究合作伙伴已通过 SQUID、同步加速器 X 射线衍射、X 射线磁圆二色性和偏振中子反射计对本征跃迁进行了表征。我们现在寻求利用 NSF-EPSRC 的联合支持来巩固这种联系，并进行一些新颖的实验，寻求使用外在参数来控制 AF-F 相变。在我们目前拥有的薄膜中，众所周知，相界的位置可以通过精确的 FeRh 化学计量本质上控制。文献中出现了一些诱人的结果，其中通过构建结合磁结构材料的异质结构，转变受到其他外部参数的显着影响。在这里，我们将通过探索这种异质结构以及 FeRh 对外在应变、静磁和交换场的响应来阐明磁结构响应的基本机制，并寻求将它们结合起来以相互增强的方法。