Spectroscopic imaging of unconventional superconductors at ultra-low temperatures

超导性是一种自Onnes于1911年发现以来就引起科学界兴趣的性质[1]。BCS超导理论描述了“传统”超导体的性质[2]，它描述了声子如何介导电子对之间的吸引力相互作用-这导致了超导性。然而，许多材料不属于传统超导体的范畴，在传统超导体中，吸引力的电子相互作用不是声子介导的。这种材料，例如高温铜氧化物超导体，被称为非常规超导体。我们还可以将超导材料分为自旋单线态或自旋三线态（取决于每个电子对中两个电子的自旋）-这两种类别会产生不同的特性和潜在的应用。所有自旋三重态超导体都是非常规的，在量子超级计算中具有令人兴奋的潜在应用，但尚未得到实验证实[3]。扫描隧道显微镜（STM）可用于通过测量态密度和研究材料的表面来研究诸如超导性的性质[4-6]。该项目旨在研究超导性分类不明确的材料（例如，自旋单线态与自旋单线态），如Sr 2 RuO 4，以提供未来潜在应用的清晰度。[1]货车德尔夫特，D. Kes，P.超导性的发现。Physics Today 63，38-43（Sept. 2010）. [2]巴丁，J.，库珀湖N. & Schrieffer，J. R.超导的微观理论。物理评论106，162-164（1957年4月）。[3]Devoret，M. H. & Schoelkopf，R.量子信息的超导电路：展望。Science 339，1169-1174（2013）. [4]霍夫曼，J.E. Bi 2Sr 2CaCu 2 O 8-中的成像准粒子干涉。Science 297，1148 -1151（2002年8月）。[5]Hanaguri，T.等.准粒子散射离开涡旋探测的高TC铜酸盐中的相干因子。Science 323，923-926（2009年2月）。[6]Kreisel，A.等，铜酸盐中扫描隧道准粒子干涉和杂质态的解释。物理评论快报114，217022（2015年5月）。

Superconductivity is a property that has intrigued the scientific community since it's discovery by Onnes in 1911 [1]. The BCS theory of superconductivity describes the properties of 'conventional' superconductors [2], which describes how phonons mediate an attractive interaction between pairs of electrons - which leads to superconductivity. Many materials, however, fall outside this realm of conventional superconductor, where the attractive electronic interaction is not phonon-mediated. Such materials, for example the high-temperature cuprate superconductors, are known as unconventional superconductors. We can also categorise superconducting materials as spin-singlet or spin-triplet (depending on the spins of the two electrons in each electron pair) - these two categories give rise to different characteristics and potential application. All spin-triplet superconductors would be unconventional and have exciting potential applications in quantum supercomputing, but are yet to be confirmed experimentally [3]. Scanning tunnelling microscopy (STM) can be used to investigate properties such as superconductivity through measuring the density of states and investigating the surfaces of materials [4-6]. This project aims to investigate materials with unclear superconductivity categorisation (e.g., spin-singlet vs. spin-singlet), such as Sr2RuO4, to provide clarity on future potential applications.[1] Van Delft, D. & Kes, P. The discovery of superconductivity. Physics Today 63, 38-43 (Sept.2010).[2] Bardeen, J., Cooper, L. N. & Schrieffer, J. R. Microscopic Theory of Superconductivity. Phys-ical Review 106, 162-164 (Apr. 1957).[3] Devoret, M. H. & Schoelkopf, R. J. Superconducting Circuits for Quantum Information: AnOutlook. Science 339, 1169-1174 (2013).[4] Hoffman, J. E. et al. Imaging Quasiparticle Interference in Bi2Sr2CaCu2O8- . Science 297,1148-1151 (Aug. 2002).[5] Hanaguri, T. et al. Coherence Factors in a High-TC Cuprate Probed by Quasi-Particle Scat-tering Off Vortices. Science 323, 923-926 (Feb. 2009).[6] Kreisel, A. et al. Interpretation of Scanning Tunneling Quasiparticle Interference and ImpurityStates in Cuprates. Physical Review Letters 114, 217022 (May 2015).