Using Disorder to Identify Bogoliubov Fermi-Surface States.

Area of Science:

• Condensed Matter Physics
• Superconductivity
• Materials Science

Background:

• Identifying exotic superconducting states is crucial for understanding novel electronic phenomena.
• Distinguishing between different types of nodal superconducting states, particularly those with Bogoliubov quasiparticles, remains a challenge.
• The influence of disorder on electronic properties is a key factor in characterizing superconducting states.

Purpose of the Study:

• To propose a method for identifying superconducting states with a Bogoliubov Fermi surface (BG-FS).
• To establish a unique experimental signature for BG-FS states based on their response to disorder.
• To provide a framework for analyzing candidate BG-FS materials.

Main Methods:

• Theoretical analysis of physical quantities' dependence on disorder in superconducting states.
• Focus on the residual density of states at weak disorder as a distinguishing feature.
• Investigation of supercurrent stability and optical conductivity behavior.

Main Results:

• A linear dependence of the residual density of states on weak disorder uniquely identifies a BG-FS state.
• Demonstration of supercurrent stability against impurities in BG-FS states.
• Observation of Drude-like behavior in the optical conductivity of BG-FS states.

Conclusions:

• The dependence of physical quantities on disorder provides a robust method for identifying BG-FS states.
• The proposed signatures offer direct experimental probes for candidate materials.
• These findings are applicable to materials like Sr$_{2}$RuO$_{4}$, FeSe$_{1-x}$S$_{x}$, and UBe$_{13}$.