Structural Effects on Spin-Polarized Quantized Conductance in Atomic-Sized Magnetic Contacts

原子尺寸磁接触中自旋极化量子化电导的结构效应

• 批准号: 0706074
• 负责人: Zonglu Susan Hua
• 金额: $ 51万
• 依托单位: SUNY at Buffalo
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0706074&HistoricalAwards=false
• 关键词: Structural; Effects; Spin; Polarized; Quantized

TECHNICAL: Fundamental investigation of atomic-sized magnetic point contacts made of transition metals (such as Co and Ni) is a fertile ground for exploring new phenomena that are either entirely new or quantum analogs of effects observed in larger ensembles. The intellectual excitement lies in building a new knowledge base for the nascent field of nano- and atomic-scale spintronics. Currently, no direct understanding exists between the spin-polarized quantized conductance/magneto-conductance and underlying contact diameter/geometry. This gap is due to the previous unavailability of stable contacts. This barrier has been overcome from PI's previous studies, paving the way for such systematic studies. Specifically, this project is focused on gaining fundamental understanding of 'structure-property' relationship in atomic-sized quantum conductors, namely, relationship between contact diameter/geometry, multivalent state, and magnetic structure versus spin-polarized quantized conductance, magnetoresistance, and their temperature-dependence, using Co and Ni. The spin-polarized quantized physical properties will be directly correlated with the underlying contact geometry/structure using high-resolution transmission electron microscopy with in-situ quantized conductance measurements. Spin-polarized electron transmission across atomic-sized magnetic conductors can open new vistas for conceiving novel electronic devices that are far more intricate, dense, fast, and robust. The same force that produces magnetism can be harnessed to create 'valves' or 'gates' across an atom to regulate charge transport, in effect, making such an atomic-scale device a microcosm of a modern day electronic circuitry. NON-TECHNICAL: The atomic-sized spintronics devices have potential applications in data storage. The same quantum exchange force also causes shifts in electronic levels, which in turn can alter electronegativity and excitation states - key factors to a fundamental understanding of elemental chemisorption, catalysis, and enzymatic reactions in biology. Education and outreach efforts will involve hands-on training for graduate, undergraduate, and high-school students in PI's laboratories. Outreach activities will include PI's participation in the SUNY-wide Louis Stokes Alliance for Minority Program for minority undergraduate students. A three to five-week summer apprentice program for minorities and women students from Buffalo-area inner city high schools will be offered. PI will develop a lecture/hands-on experimental module called "Discreteness of matter" using gold atomic-sized conductors, targeting both high-school students and undergraduate students. Module will demonstrate how conductance eventually becomes discrete (quantized) at atomic scale. Few experiments in science exist where quantum effects can be so readily demonstrated at room temperature, and with ease. The module would also allow ratio of two of the most fundamental constants (electron charge and Planck constant) to be measured directly - the unit of quantized conductance, and will be highlighted.

技术支持：由过渡金属（如Co和Ni）制成的原子大小的磁点接触的基础研究是探索新现象的肥沃土壤，这些新现象要么是全新的，要么是在更大的集合中观察到的效应的量子类似物。智力上的兴奋在于为纳米和原子尺度的自旋电子学的新生领域建立一个新的知识基础。目前，在自旋极化的量子化电导/磁导和潜在的接触直径/几何形状之间不存在直接的理解。这一差距是由于以前没有稳定的联系人。PI以前的研究已经克服了这一障碍，为这种系统的研究铺平了道路。具体而言，该项目的重点是获得原子大小的量子导体中的“结构-性质”关系的基本理解，即接触直径/几何形状，多价态和磁结构与自旋极化量子化电导，磁阻及其温度依赖性之间的关系，使用Co和Ni。自旋极化的量子化的物理性质将直接相关的底层接触几何形状/结构，使用高分辨率透射电子显微镜与原位量子化电导测量。通过原子大小的磁导体的自旋极化电子传输可以为构思更复杂，更密集，更快，更坚固的新型电子设备开辟新的前景。产生磁性的同一种力可以用来在原子上创建“阀门”或“门”，以调节电荷传输，实际上，使这种原子级设备成为现代电子电路的缩影。非技术性：原子大小的自旋电子器件在数据存储方面有潜在的应用。同样的量子交换力也会引起电子能级的变化，这反过来又会改变电负性和激发态--这是基本理解生物学中元素化学吸附、催化和酶反应的关键因素。教育和推广工作将包括在PI实验室对研究生、本科生和高中生进行实践培训。外展活动将包括PI参与纽约州立大学范围内的路易斯斯托克斯少数民族计划联盟，为少数民族本科生。将为布法罗地区内城高中的少数民族和女学生提供为期三到五周的暑期学徒计划。PI将开发一个讲座/动手实验模块，称为“离散的物质”使用黄金原子大小的导体，针对高中生和本科生。模块将演示如何电导最终成为离散（量子化）在原子尺度。在科学实验中，很少有量子效应可以在室温下如此容易地证明。该模块还允许直接测量两个最基本的常数（电子电荷和普朗克常数）的比值-量子化电导的单位，并将突出显示。