Magnetoimpedance of Ultrathin Films and Thin-Film Interfaces

技术摘要：在这项个人研究资助中，我们利用复阻抗测量技术来表征磁场对薄膜结构中电输运的影响。正在研究的具体主题是：(1)由现场异常霍尔测量监测的在极端无序极限中巡回铁磁性的崩溃，(2)界面磁电容对宿主PD电极中超薄掩埋铁层表面接近性的贡献的敏感性，(3)在使用标准和磁性半导体制造的轻掺杂MOS和肖特基势垒结构中迄今未被认识到的巨大磁电容贡献，以及(4)在各向异性或层状相关电子系统中复介电常数的频率响应的获取和分析，其中绝缘相与具有磁性的金属相竞争(例如，锰氧化物)或超导(低掺杂高T_c)。预计结果将为理解复杂材料界面的磁性提供相当大的洞察力，这些材料显示出在磁电子学和纳米技术中的应用前景。从事这个项目的学生将在科学界传播他们的成果，并学习在工业、政府或学术环境中非常有市场的薄膜生长和表征技能。非技术摘要：这项拟议的工作将专注于理解平面界面上的磁性物理，使用电测量技术，可以同时检测磁场对电子迁移率和存在的电子数量的影响。对于我们的目的，界面主导的磁性系统可以是超薄磁性薄膜，两种不同材料之间的平面界面，具有磁性电极的隧道结，或者其中至少有一个是磁性的共存和竞争相存在的块体系统。对这一提议中涉及的科学问题的回答，例如“磁性如何在界面上存活？”，“在铁磁有序消失之前，一个系统可以做得多小？”以及“面向自旋的电子在界面上的转移效率有多高？”，有望帮助我们理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、政府或学术环境中非常有市场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.