Scanning Tunneling Spectroscopy Studies of Organic Superconductors

*** Bechgaard盐是一种一维有机导体，它显示了凝聚态物理学中已知的大多数电子相。该项目将使用扫描隧道显微镜（STM）来研究一种这样的材料，（TMTSF）2ClO4，它在低于1.5 K的温度下具有超导性。通常情况下，超导性会被高磁场破坏，但在这种情况下，超导性可以通过两种不寻常的尚未证实的效应保持到任意高的磁场：三重态配对和场诱导的一维性。三重态超导也被提出作为量子计算的一条途径。该合同将资助在氦冰箱上建造一个超稳定STM，温度控制低至250 mK，低温切割器可以暴露干净的表面，同时传输测量能力和三轴磁场。原子分辨STM图像中的特定能量特征可能为三重态超导性提供确凿的证据。该项目的更广泛影响将包括对本科生和研究生的培训，以及一个致力于为非专业人士澄清有机超导体并为专家编制其可量化特性的网站。***技术摘要***该个人研究者奖将资助对Tc = 1.5 K的准一维有机超导体Bechgaard盐（TMTSF）2ClO4的扫描隧道显微镜（STM）研究。三重态超导性和场致维度交叉的独特汇合可能使沿一个晶体轴的上临界场Hc2基本上是无限的，但是三重态超导性仍然没有得到证实。PI将在3He冰箱上建立一个超稳定的STM，具有可变温度控制，低温切割以暴露清洁表面，同时传输测量能力和三轴磁场。本实验将使用干净的真空隧道结，经原子分辨率验证，探测三重态超导的Andreev束缚态特征。该项目还将尝试用磁性或非磁性杂质生长（TMTSF）2ClO4，并根据单三重态争论研究它们的局部效应。该项目的更广泛影响将包括对本科生和研究生的培训，以及一个致力于为非专业人士澄清有机超导体并为专家编制其可量化特性的网站。

*** NON-TECHNICAL ABSTRACT ***The Bechgaard salts are one-dimensional organic conductors which display most of the electronic phases known in condensed matter physics. This project will use a scanning tunneling microscope (STM) to study one such material, (TMTSF)2ClO4, which superconducts at temperatures below 1.5 K. Ordinarily, superconductivity is destroyed by a high magnetic field, but in this case superconductivity may be preserved up to arbitrarily high fields by two unusual yet unproven effects: triplet pairing, and field-induced one-dimensionality. Triplet superconductivity has also been proposed as a route to quantum computing. This award will fund construction of an ultra-stable STM on a helium fridge, with temperature control down to 250 mK, low temperature cleaver to expose clean surfaces, simultaneous transport measurement capabilities, and a triple-axis magnetic field. Specific energy features in the atomically resolved STM images may provide the smoking gun signature for triplet superconductivity. The broader impact of this project will include training of undergraduate and graduate students, and a website dedicated to clarifying organic superconductors for non-experts and tabulating their quantifiable properties for experts.***TECHNICAL ABSTRACT ***This individual investigator award will fund a scanning tunneling microscopy (STM) study of the Bechgaard salt (TMTSF)2ClO4, a quasi-one-dimensional organic superconductor with Tc = 1.5 K. A unique confluence of triplet superconductivity and field-induced dimensional crossover may render the upper critical field Hc2 essentially infinite along one crystal axis, however triplet superconductivity remains unproven. The PI will build an ultra-stable STM on a 3He fridge, with variable temperature control, low temperature cleaver to expose clean surfaces, simultaneous transport measurement capabilities, and triple-axis magnetic field. This experiment will use clean vacuum tunnel junctions, verified with atomic resolution, to probe for the Andreev bound state signature of triplet superconductivity. The project will also attempt to grow (TMTSF)2ClO4 with magnetic or non-magnetic impurities, and to study their local effects, in light of the single-triplet debate. The broader impact of this project will include training of undergraduate and graduate students, and a website dedicated to clarifying organic superconductors for non-experts and tabulating their quantifiable properties for experts.