Magnetoimpedance of Ultrathin Films and Thin-Film Interfaces

技术摘要：在这个个人研究补助金，我们利用复阻抗测量技术来表征薄膜结构中的电输运磁场的影响。正在研究的具体专题是：（1）通过原位反常霍尔测量监测到的极端无序极限中巡游铁磁性的崩溃，（2）界面磁电容贡献对主体Pd电极中的无序掩埋Fe层的表面邻近的敏感性，（三）迄今为止未被认识到的“巨”磁电容贡献轻掺杂MOS和肖特基势垒结构制造使用标准和磁性半导体;以及（4）在绝缘相与金属相竞争的各向异性或分层相关电子系统中获得和分析复介电常数的频率响应，所述金属相或者是磁性的（例如，锰氧化物）或超导（低掺杂高Tc）。结果预计将提供相当深入的了解磁性能的复杂材料，显示用于磁电子学和纳米技术的承诺的接口。从事该项目的学生将在科学界传播他们的成果，并学习薄膜生长和表征技能，这些技能在工业、政府或学术环境中非常有市场。非技术摘要：这项拟议的工作将侧重于理解磁性在平面界面的物理学，使用电测量技术，可以同时感测磁场对电子迁移率和电子数量的影响。对于我们的目的，界面主导的磁性系统可以是磁性薄膜，两种不同材料之间的平面界面，具有磁性电极的隧道结，或者其中存在共存和竞争相的体系统，其中至少一个是磁性的。对该提案中提出的科学问题的回答，例如“磁性如何在界面处生存？“，“在铁磁有序消失之前，一个系统可以做得多小？以及“自旋取向的电子在界面上传输的效率如何？““，预计将有助于了解磁电子学在未来技术中的潜力。从事该项目的学生将在科学界传播他们的成果，并学习在工业，政府或学术环境中极具市场价值的薄膜生长和表征技能。

Technical Abstract:In this individual investigator grant we utilize complex impedance measurement techniques to characterize the effect of magnetic fields on electrical transport in thin-film structures. The particular topics under study are: (1) the collapse of itinerant ferromagnetism in the extreme disorder limit as monitored by in situ anomalous Hall measurements,(2) the sensitivity of the interfacial magnetocapacitance contributions to the surface proximity of ultrathin buried Fe layers in host Pd electrodes,(3) a heretofore unrecognized 'giant' magnetocapacitance contribution in lightly doped MOS and Schottky barrier structures fabricated using both standard and magnetic semiconductors, and (4) the acquisition and analysis of the frequency response of the complex dielectric constant in anisotropic or layered correlated electron systems where insulating phases compete with metallic phases that are either magnetic (e.g.,manganites) or superconducting (underdoped high Tc). Results are expected to give considerable insight into understanding magnetic properties at the interfaces of complex materials that show promise for use in magnetoelectronics and nanotechnology. Students working on this project will disseminate their results within the scientific community and learn thin-film growth and characterization skills that are highly marketable in industrial, government or academic environments.Non-Technical Abstract:This proposed work will focus on understanding the physics of magnetism at planar interfaces using electrical measurement techniques that can simultaneous sense the effect of magnetic field on the mobility of electrons and on the number of electrons present. For our purposes an interface-dominated magnetic system can be an ultrathin magnetic film, a planar interface between two dissimilar materials, a tunnel junction with magnetic electrodes, or a bulk system in which there are coexisting and competing phases, at least one of which is magnetic. Answers to scientific questions addressed in this proposal, such as "How does magnetism survive at interfaces?", "How small can a system be made before ferromagnetic ordering disappears?" and "How efficiently can spin-oriented electrons be transferred across an interface?", are expected to help provide an understanding of the potential of magnetoelectronics in future technology. Students working on this project will disseminate their results within the scientific community and learn thin-film growth and characterization skills that are highly marketable in industrial, government or academic environments.