Coherent Thermal and Electrical Transport in Mesoscopic Structures

*****非技术摘要******电子电路的日益小型化使得计算机的速度更快，手机的体积更小，但目前电子电路的小型化面临两个问题：使今天的技术更小的障碍是什么？基于量子效应的新型设备能否被制造出来？这个个人研究者奖支持一个将解决这两个问题的项目。缩小现有设备的最大障碍之一是，随着计算机芯片变得越来越小，它们的热量也越来越高。为了解决这个问题，我们提出的研究将试图理解纳米尺度上导线的热传导背后的基本物理原理，这似乎与较大导线的热传导不同。这项研究将通过观察不同材料之间的相互作用，在足够小的尺寸尺度上，这些材料之间的量子相互作用产生新的物理效应，从而推动从根本上推动新型设备的发展，这些物理效应可以用于未来的技术。除了培养研究生和博士后外，该项目还将培养本科生和高中生在微观和纳米尺度上制作物体的基本技术。*****技术摘要******该个人研究者奖支持一个探索由超导(S)、正常金属(N)和铁磁(F)材料组成的金属介观异质结构的电学和热性能的项目。电输运实验将研究由材料之间的接近效应引起的一系列相干过程。这些实验将包括研究FSF器件中的三重态超导性，NSN和FSF器件中的非局部Andreev反射，以及SNS器件中的可调谐pi结。热输运实验将继续对纳米尺度结构中的异常行为进行先前的观察，包括正常金属导线中对Wiedemann-Franz定律的可能偏差，以及Andreev干涉仪热功率中无法解释的对称性。这些器件的最关键的制造步骤和毫开尔文温度测量将由研究生和博士后承担，而一些纳米和微制造步骤将由本科生和当地高中生完成，训练他们掌握电子束和光刻的基础知识。

*****NON-TECHNICAL ABSTRACT******The increasing miniaturization of electronic circuitry that allows the development of faster computers and slimmer cell phones is presently facing two questions: what impediments are there to making today's technology even smaller? and can fundamentally new types of devices, based on quantum effects, be manufactured? This individual investigator award supports a project that will address both of these questions. One of the biggest obstacles to shrinking current devices is that as computer chips get smaller and smaller they heat up more and more. In addressing this problem the proposed research will attempt to understand the basic physics behind heat conduction for wires that are on the nanometer scale, which appears to differ from heat conduction in larger wires. This research will advance the drive towards fundamentally new types of devices by looking at the interplay between different materials on size scales small enough that the quantum interactions between these materials yield new physical effects that could be harnessed for future technologies. In addition to training graduate students and post-docs, this project will train undergraduates and high school students in basic techniques for making objects on the micro- and nanoscales.*****TECHNICAL ABSTRACT******This individual investigator award supports a project exploring the electrical and thermal properties of metallic, mesoscopic heterostructures composed of superconducting (S), normal-metal (N), and ferromagnetic (F) materials. The electrical transport experiments will examine a broad array of coherent processes caused by proximity effects between the materials. These experiments will include investigations into triplet superconductivity in FSF devices, non-local Andreev reflection in NSN and FSF devices, and tunable pi-junctions in SNS devices. The thermal transport experiments will pursue prior observations of anomalous behavior in nanoscale structures, including possible deviations from the Wiedemann-Franz law in normal-metal wires and unexplained symmetries in the thermopower of Andreev interferometers. While the most critical fabrication steps and milliKelvin temperature measurements of these devices will be undertaken by graduate students and post-docs, some nano- and microfabrication steps will be performed by undergraduate and local high school students, training them in the basics of e-beam and photolithography.