Spectroscopic imaging of unconventional superconductors at ultra-low temperatures

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.

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[5] Hanaguri, T. et al. Coherence Factors in a High-TC Cuprate Probed by...