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

技术：由过渡金属(如钴和镍)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，这些现象要么是全新的，要么是在更大的系综中观察到的效应的量子模拟。知识界的兴奋之处在于为新生的纳米和原子尺度自旋电子学领域建立了一个新的知识库。目前，在自旋极化的量子化电导/磁导与其下的接触直径/几何形状之间没有直接的理解。这一差距是由于之前没有稳定的联系人造成的。这一障碍已经从Pi以前的研究中被克服了，为这样的系统研究铺平了道路。具体地说，本项目的重点是通过使用Co和Ni，从根本上了解原子大小的量子导体中的结构-性质关系，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、磁阻及其温度关系的关系。使用具有原位量化电导测量的高分辨率透射电子显微镜，自旋极化的量子化物理性质将与潜在的接触几何/结构直接相关。原子大小的磁导体之间的自旋极化电子传输可以为构思更加复杂、密集、快速和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被用来在一个原子上创造一个“阀”或“门”来调节电荷的传输，实际上，使这样一个原子尺度的设备成为现代电子电路的一个缩影。非技术性：原子大小的自旋电子学设备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，这反过来又可以改变电负性和激发状态--这是从根本上理解生物学中的元素化学吸附、催化和酶反应的关键因素。教育和外展工作将包括在PI的实验室对研究生、本科生和高中生进行实践培训。外展活动将包括派参加全纽约州立大学为少数族裔本科生设立的路易斯·斯托克斯少数族裔联盟方案。将为布法罗地区市中心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将利用金原子大小的导体开发一个名为“物质的离散性”的讲座/动手实验模块，面向高中生和本科生。模块将演示电导如何最终在原子尺度上离散(量子化)。在科学实验中，很少有实验可以在室温下如此轻松地证明量子效应。该模块还将允许直接测量两个最基本的常数(电子电荷和普朗克常数)的比率-量化的电导单位，并将突出显示。

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.