Generalized Anderson's theorem for superconductors derived from topological insulators

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Nodal superconductors are typically sensitive to nonmagnetic impurities.
• Recent observations show Bi2Se3-based topological superconductors resist disorder unexpectedly.

Purpose of the Study:

• To develop a theoretical framework explaining the robustness of complex superconductors against disorder.
• To generalize Anderson's theorem for superconductors with multiple internal degrees of freedom.

Main Methods:

• Developed a theoretical framework based on superconducting fitness.
• Generalized Anderson's theorem using the Born approximation.
• Analyzed the Cu(PbSe)5(BiSe3)6 superconductor as an extreme example.

Main Results:

• Provided a theoretical explanation for the unusual robustness of certain nodal superconductors.
• Experimental data from thermal conductivity measurements confirmed the presence of nodes.
• Observed scattering rates orders of magnitude larger than the superconducting energy gap.

Conclusions:

• The generalized Anderson's theorem effectively protects nodal superconductors from strong scattering.
• The Cu(PbSe)5(BiSe3)6 superconductor represents a unique case study for this phenomenon.