Ferromagnetic Impurity Induced Majorana Zero Mode in Iron-Based Superconductor

Abstract

Recent experiments reported the puzzling zero energy modes associated with ferromagnetic impurities in some iron-based superconductors with topological band structures. Here, we show that the sufficiently strong exchange coupling between a ferromagnetic impurity and substrate can trigger a quantum phase transition, beyond which, the phase of the topological surface superconducting order parameter around the impurity acquires a sign-change. In such a case, we prove that a Kramers degenerate pair of Majorana modes can be induced at the boundary separating the two sign-change regimes and trapped around the impurity in the topological surface superconducting state. Furthermore, we show that our theory can explain the controversial observations and confusing features of the zero energy modes from recent experiments in some iron-based superconductors.

6+13 pages, 4+11 figures

References in corpus (8)

• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• A minimal two-band model for the superconducting Fe-pnictides
• Observation of a Robust Zero-energy Bound State in Iron-based Superconductor Fe(Te,Se)
• Spin-polarized Yu-Shiba-Rusinov states in an iron based superconductor
• Topological Phases in the Single-Layer FeSe
• Z2 invariant protected bound states in topological insulators
• Robustness of Majorana Modes and Minigaps in a Spin-Orbit-Coupled Semiconductor-Superconductor Heterostructure
• Phase-manipulation-induced Majorana Mode and Braiding Realization in Iron-based Superconductor Fe(Te,Se)

Cited by in corpus (2)

• Stealth Majorana Zero Mode in a Trilayer Heterostructure MnTe/Bi2Te3/Fe(Te,Se)
• Magnetic-field driven evolution of zero-energy mode on Bi islands deposited on Fe(Te,Se)