Crystalline symmetry protected helical Majorana modes in the iron pnictides

Abstract

We propose that propagating one-dimensional Majorana fermions will develop in the vortex cores of certain iron-based superconductors, most notably Li(Fe${}_{1-x}$Co${}_x$)As. A key ingredient of this proposal are the 3D Dirac cones recently observed in ARPES experiments [P. Zhang et al., Nat. Phys. $\text{15}$, 41 (2019)]. Using an effective Hamiltonian around the $\Gamma -Z$ line we demonstrate the development of gapless one-dimensional helical Majorana modes, protected by $C_4$ symmetry. A topological index is derived which links the helical Majorana modes to the presence of monopoles in the Berry curvature of the normal state. We present various experimental consequences of this theory and discuss its possible connections with cosmic strings.

4 pages + Supplement. Accepted in Phys. Rev. Lett

References in corpus (11)

• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Topological Insulators with Inversion Symmetry
• Classification of topological insulators and superconductors in three spatial dimensions
• Topological Defects and Gapless Modes in Insulators and Superconductors
• Topological Phases of Noncentrosymmetric Superconductors: Edge States, Majorana Fermions, and the Non-Abelian Statistics
• Observation of a Robust Zero-energy Bound State in Iron-based Superconductor Fe(Te,Se)
• Topological spin-current in non-centrosymmetric superconductors
• Scanning Tunneling Microscopy/Spectroscopy of Vortices in LiFeAs
• Axion topological field theory of topological superconductors
• Flat band in the core of topological defects: bulk-vortex correspondence in topological superfluids with Fermi points

Cited by in corpus (2)

• On the Remarkable Superconductivity of FeSe and its Close Cousins
• Quantum phase transition of correlated iron-based superconductivity in LiFe${}_{1-x}$Co${}_x$As