RUI: Critical Dynamics of the Electron-Doped Cuprate Superconductors

技术：电压与电流曲线的标度分析是研究正常超导相变的宝贵工具。然而，最近的工作表明，该工具的传统应用过于灵活，无法唯一地确定关键参数，并且外部影响可能模糊或破坏相变。有了这些警告，我们可以更仔细地应用这些工具来确定正常超导相变的关键参数，无论是在场还是在零场。该个人研究者奖支持一个项目，该项目将把这些工具应用于一种新型材料：电子掺杂超导体Pr2-xCexCuO4-y （PCCO）。本项目将研究PCCO的关键动力学作为掺杂和场的函数。PCCO表现出一系列有趣的行为，如d波到s波配对、向绝缘态的过渡和量子临界点。这些现象中的任何一种都可能影响相变动力学。这个项目将增加我们对电子掺杂超导体相变的理解，特别是解释为什么电子掺杂材料的行为与空穴掺杂材料的行为如此不同。该项目还将对本科生进行实验和低温物理方面的培训，并将为当地公立学校现有的推广计划做出贡献，以鼓励更广泛的科学教育。非技术：二十多年前发现的高温超导体，仍然有着巨大的希望和巨大的挑战。希望在于最终制造出具有更高转变温度的超导体，而挑战在于，即使在20年后，我们也没有完全理解这些材料是如何或为什么超导的。众所周知，超导体可以用两种类型的电荷载体来制造或“掺杂”：电子，或者缺少电子留下的空间，称为“空穴”。电子和空穴作为电荷载体在理论上没有区别，然而，空穴掺杂超导体的转变温度要高得多，并且在其他几个方面与它们在理论上相同的同伴——电子掺杂超导体不同。这个个人研究者奖支持一个项目，该项目将研究新型电子掺杂材料如何成为超导材料，希望了解这些材料产生超导性的潜在机制。提出的研究将增加对高温超导体的认识，并有望实现更高的转变温度。该项目还将培训本科生掌握最先进的薄膜生长、表征和测量技术，并将通过在当地小学增加科学推广和在高级实验课程中增加低温物理学，为更广泛的教育目标做出贡献。

Technical:The scaling analysis of voltage vs. current curves has been an invaluable tool in the study of the normal-superconducting phase transition. However, recent work has shown that the conventional application of this tool is too flexible to uniquely determine the critical parameters, and that extrinsic effects can obscure or destroy the phase transition. With these caveats known, we can more carefully apply the tools to determine the critical parameters of the normal-superconducting phase transition, both in a field and in zero field. This individual investigator award supports a project that will apply these tools to a novel material: the electron-doped superconductor Pr2-xCexCuO4-y (PCCO). This project will study the critical dynamics of PCCO as a function of doping and field. PCCO has displayed an array of interesting behaviors, such as d- to s-wave pairing, a transition to an insulating state, and a quantum critical point. Any and all of these phenomena may affect the dynamics of the phase transition. This project will add to our understanding of the phase transition in electron-doped superconductors, and in particular, explain why the electron-doped materials behave so differently from their hole-doped counterparts. This project will also train undergraduate students in experimental and low-temperature physics and will contribute to an existing outreach program with local public schools to encourage broader education in science.Non-Technical:High-temperature superconductors, discovered more than two decades ago, still hold great promise and great challenges. The promise lies in the hope of eventually making superconductors with much higher transition temperatures, and the challenges lie in the fact that we do not, even two decades later, fully understand how or why these materials superconduct. It is known that superconductors can be made, or "doped," with two types of electric charge carriers: electrons, or the space left by the lack of an electron, called a "hole." There is no theoretical difference between electrons and holes as charge carriers, and yet, hole-doped superconductors have much higher transition temperatures and are different in several other ways than their theoretically identical companions, electron-doped superconductors. This individual investigator award supports a project that will study how novel electron-doped materials become superconducting, in the hopes of understanding the underlying mechanism that creates superconductivity in these materials. The proposed studies will add to the knowledge of high-temperature superconductors and held fulfill the promise of attaining higher transition temperatures. This project will also train undergraduate students in state-of-the-art film growth, characterization, and measurement techniques, and will contribute to broader educational goals by adding science outreach to local elementary schools and adding low-temperature physics to advanced laboratory courses.