Tomographic imaging of superconducting order using particle-hole interference.

Area of Science:

• Condensed Matter Physics
• Superconductivity Research
• Materials Science

Background:

• Superconducting phases with symmetries distinct from their crystal lattice are of significant research interest.
• Detecting the order parameter symmetry and topology of superconductors is a persistent challenge.
• While scanning tunneling microscopy (STM) reveals superconducting gap nodes, it cannot access order parameter phase winding.

Purpose of the Study:

• To introduce a novel scanning tunneling microscopy (STM) technique for imaging superconducting order parameter phase winding.
• To enable the reconstruction of the momentum-space structure of the superconducting gap function.
• To provide a method for distinguishing between competing superconducting order parameter candidates.

Main Methods:

• Exploiting Young-type quasiparticle interference patterns generated by pairs of impurities acting as beam splitters.
• Utilizing Superconducting Order Parameter Tomography (SOPT), which analyzes the response of Bogoliubov quasiparticle interference patterns to impurity configuration rotations.
• Applying SOPT to Strontium Ruthenate to differentiate between potential superconducting order parameters.

Main Results:

• Demonstrated that STM can access superconducting order parameter phase winding information.
• Developed SOPT for reconstructing the momentum-space gap function structure.
• Showcased SOPT's ability to distinguish between competing order parameter candidates in Strontium Ruthenate.

Conclusions:

• Superconducting Order Parameter Tomography (SOPT) provides access to phase winding information previously inaccessible by STM.
• SOPT enables the reconstruction of the superconducting gap function's momentum-space structure.
• This particle-hole interference-based method offers a new imaging modality for identifying unconventional and topological superconductivity.