Dislocation Majorana bound states in iron-based superconductors.

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Topological Superconductivity

Background:

• Recent experiments reveal coexisting weak topology, surface magnetism, and superconductivity in FeTe$_{1-x}$Se$_{x}$.
• Topological superconductors host exotic quasiparticles with potential applications in quantum computing.

Purpose of the Study:

• To theoretically demonstrate that lattice dislocations in topological iron-based superconductors can intrinsically trap non-Abelian Majorana quasiparticles.
• To explore emergent higher-order topological phases and their defect-bound Majorana modes.

Main Methods:

• Theoretical modeling of topological iron-based superconductors.
• Development of a nested domain wall theory to explain defect Majorana zero modes.
• Analysis of emergent second-order topological superconductivity in 2D subsystems.

Main Results:

• Lattice dislocations in topological iron-based superconductors intrinsically trap non-Abelian Majorana quasiparticles.
• Emergent second-order topological superconductivity in 2D subsystems of dislocations.
• Identification of defect-bound Majorana zero modes and Majorana Kramers pairs.

Conclusions:

• Lattice defects provide a novel platform for realizing higher-order topological phases.
• Material defects can serve as a new route for high-temperature topological quantum information processing.
• Proposed mechanisms are relevant to materials like FeTe$_{1-x}$Se$_{x}$, LiFeAs, and β-PdBi$_{2}$.