Observation of Majorana zero modes emerged from topological Dirac semimetal states under uniaxial strain

TL;DR

This study demonstrates that uniaxial strain can induce Majorana zero modes in the bulk of a topological Dirac semimetal within an iron-based superconductor, providing a new way to engineer Majorana physics.

Contribution

It reveals that uniaxial strain can generate Majorana zero modes from the bulk topological Dirac semimetal state in LiFeAs, a novel approach in superconductor research.

Findings

Uniaxial strain enhances band renormalization in LiFeAs.

Strain reduces energy gap between Fermi level and Dirac state.

Observation of Majorana zero modes via scanning tunneling microscopy.

Abstract

The topological properties observed in iron-based superconductors extend our understanding of vortex Majorana quasiparticle excitations in unexpected ways. Vortex Majorana physics has been extensively studied within the context of the topologically protected surface Dirac state. By employing an in-situ strain device, we demonstrate that uniaxial strain can generate Majorana zero modes out of the topological Dirac semimetal bulk state in LiFeAs. Uniaxial strain along [100] direction is found to enhance the band renormalization of LiFeAs, effectively reducing the energy separation between the Fermi level and the topological Dirac semimetal state, and breaking C4 symmetry. Using scanning tunneling microscopy, we observe the evolution of vortex bound states in the topological Dirac semimetal state region, accompanied by the emergence of Majorana zero modes and vortex bound states contributed by the bulk band. Our work provides a controllable method for experimentally engineering Majorana physics in iron-based superconductors, and offers valuable insights into the topological Dirac semimetal state with intrinsic s-wave superconductivity.