RUI: Fluctuations and Phase Transitions in Iron Pnictide Superconductors

*技术摘要*该奖项支持本科院校的实验低温物理研究。电压-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，这种工具的常规应用过于灵活，无法唯一地确定临界参数，而且外部效应可以掩盖或破坏相变。有了这些注意事项，我们已经成功地应用这一技术研究了空穴掺杂铜酸盐YBa2Cu3O7和电子掺杂铜酸盐Pr2-xCexCuO4。这个项目将使用相同的技术来研究新的铁锡-122超导体(SrFe2As2和BaFe2As2)在磁场和零磁场中的相变。这项工作将有助于理解这种材料的相变模型，以及铁磷酸盐超导体与其他超导体相变的异同。该项目还将培训实验和低温物理方面的本科生，为研究生工作或行业职业生涯做准备。此外，为了鼓励更广泛的科学教育，该项目将促进与当地公立学校的现有外展计划，并将视频演示提交到YouTube。*非技术摘要*该奖项支持本科生机构的实验低温物理研究。四分之一个多世纪前发现的“高温”超导体，仍然有着巨大的希望和巨大的挑战。这种前景在于希望最终制造出转变温度高得多的超导体，而挑战在于，即使在25年后，我们也不能完全理解这些材料是如何或为什么超导的。2008年发现的由铁和砷制成的超导体是一系列表现出超导电性的不寻常材料中的最新一种。这一个人研究人员奖支持一个项目，该项目将研究铁和砷基材料如何成为超导，将它们与铜-氧基超导体和传统的单元素超导体进行比较，所有这些都是为了了解在这些材料中产生超导电性的潜在机制。拟议中的研究将增加对高温超导体的了解，并有助于实现实现更高转变温度的承诺。该项目还将对本科生进行最先进的样品生长、表征和测量技术的培训。该项目还将通过促进对当地学校的科学宣传和通过在线视频演示促进研究，为更广泛的教育目标做出贡献。

****Technical Abstract****This award supports experimental low-temperature physics research at an undergraduate institution. 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 have successfully applied this technique to study the hole-doped cuprate YBa2Cu3O7 and the electron-doped cuprate Pr2-xCexCuO4. This project will use the same technique to examine the phase transition in the new iron pnictide-122 superconductors (SrFe2As2 and BaFe2As2) both in a magnetic field and in zero magnetic field. This work will lead to an understanding of the model that governs the phase transition in this material and the differences and similarities of the phase transition between iron pnictide superconductors and other superconductors. This project will also train undergraduate students in experimental and low-temperature physics in preparation for graduate work or industry careers. In addition, to encourage broader education in science, this project will contribute to an existing outreach program with local public schools and submit video demonstrations to YouTube.****Non-Technical Abstract****This award supports experimental low-temperature physics research at an undergraduate institution. "High-Temperature" superconductors, discovered more than a quarter of a century 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 25 years later, fully understand how or why these materials superconduct. Superconductors made from iron and arsenic, discovered in 2008, are the latest in an array of unusual materials to display superconductivity. This individual investigator award supports a project that will study how iron- and arsenic-based materials become superconducting, comparing them to copper-oxygen based superconductors and conventional, single element superconductors, all 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 help fulfill the promise of attaining higher transition temperatures. This project will also train undergraduate students in state-of-the-art sample growth, characterization, and measurement techniques. This project will also contribute to broader educational goals by fostering science outreach to local schools and promoting the research via online video demonstrations.