Experimental Investigation of Competing Orders, Quantum Criticality and Spin/Charge Transport in Cuprate Superconductors

这个个人研究者奖是为了一个实验研究项目，该项目将解决一些与高温超导铜酸盐相关的最基本的物理问题。本文的主要目的是：利用低温扫描隧道显微镜（STM）和光谱学（STS）研究不同家族的空穴掺杂（p型）铜超导体中竞争阶数和量子临界点的可能存在与掺杂水平和温度的关系。比较电子掺杂（n型）铜酸盐超导体与电子掺杂（p型）铜酸盐超导体的配对势、配对对称性和竞争序。通过研究自旋极化和简单准粒子注入对钙钛矿铁磁-绝缘体-超导体（F-I-S）和正常金属-绝缘体-超导体（N-I-S）异质结构的影响，阐明p型铜超导体中自旋和电荷输运的特性。STM/STS优越的空间分辨率有望为铜超导体的微观特性提供独特的信息，并且对这些超导体中自旋/电荷输运的研究可以深入了解自旋和电荷自由度在其配对状态中的作用。除了这些研究对揭示铜超导的基础物理具有潜在的重大影响外，该项目所采用的广泛的前沿实验技术将为参与该项目的学生和博士后研究人员提供良好的技术和科学培训。此外，基于可变自旋极化准粒子电流下F-I-S异质结构可调谐超导特性的新型微电子器件可能被设计用于一系列应用。该个人研究者奖将资助一个实验研究项目，该项目试图解决一些最基本的物理问题和与高温超导铜酸盐相关的潜在应用。有两种主要的实验方法。其中一个涉及使用低温扫描隧道显微镜（STM）以原子尺度的空间分辨率研究铜酸盐的微观物理性质，从而证明这些非常规超导体的量子性质的直接信息。另一种实验方法涉及研究在由铁磁-绝缘体-超导体（F-I-S）和普通金属-绝缘体-超导体（N-I-S）异质结构的薄膜层组成的新型器件中，铜酸盐的各种超导性能如何在注入电流的情况下被改变。除了这些研究对揭示铜超导的基本物理具有潜在的重大影响外，该项目所采用的广泛的前沿实验技术将为参与该项目的学生和博士后研究人员提供良好的技术和科学培训。此外，在可变注入电流下，F-I-S异质结构的可调谐超导特性是各种微电子器件应用的有希望的候选者

This individual investigator award is for an experimental research project that will address some of the most fundamental physics issues associated with high-temperature superconducting cuprates. The primary objectives are: [1] To investigate the competing orders and possible existence of a quantum critical point in different families of hole-doped (p-type) cuprate superconductors as a function of the doping level and temperature by means of low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). [2] To compare the pairing potential, pairing symmetry, and competing orders in the electron-doped (n-type) cuprate superconductors with those in the p-type cuprates. [3] To elucidate the characteristics of spin and charge transport in the p-type cuprate superconductors by studying the effects of spin-polarized and simple quasiparticle injection in perovskite ferromagnet-insulator-superconductor (F-I-S) and in normal metal-insulator-superconductor (N-I-S) heterostructures. The superior spatial resolution of STM/STS is expected to provide unique information for the microscopic properties of cuprate superconductors, and the investigation of spin/charge transport in these superconductors can yield insights into the roles of spin- and charge-degrees of freedom in their pairing state. In addition to the potentially significant impact of these studies on revealing the fundamental physics of cuprate superconductivity, the wide range of forefront experimental techniques employed in conducting this project will provide sound technical and scientific training for the participating students and postdoctoral researchers. Furthermore, novel microelectronic devices based on the tunable superconducting properties of F-I-S heterostructures under variable spin-polarized quasiparticle currents may be devised for a range of applications.%%%This individual investigator award will fund an experimental research project that attempts to address some of the most fundamental physics issues and potential applications associated with high-temperature superconducting cuprates. There are two primary experimental approaches. One involves the use a low-temperature scanning tunneling microscope (STM) to study the microscopic physical properties of cuprates with atomic-scale spatial resolution, thereby proving direct information for the quantum nature of these unconventional superconductors. The other experimental approach involves studying how various superconducting properties of the cuprates are modified under the injection of electrical currents in novel devices comprising of thin-film layers of ferromagnet-insulator-superconductor (F-I-S) and normal metal-insulator-superconductor (N-I-S) heterostructures. In addition to potentially significant impact of these studies on revealing the fundamental physics of cuprate superconductivity, the wide range of frontier experimental techniques employed in conducting this project will provide sound technical and scientific training for the participating students and postdoctoral researchers. Furthermore, the tunable superconducting properties of the F-I-S heterostructures under variable injection currents are promising candidates for various microelectronic device applications.***