  Magnetic impurity chains on top of conventional superconductors are promising
platforms to realize Majorana modes. Iron-based high-temperature
superconductors are known in the vicinity of magnetic states due to the strong
Hund's coupling in iron atoms. Here we propose that the line defects with
missing Te/Se anions in Fe(Se,Te) superconductors provide the realization of
intrinsic antiferromagnetic(AFM) chains with Rashba spin-orbit coupling.
Against conventional wisdom, Majorana zero modes (MZMs) can be robustly
generated at these AFM chain ends. These results can consistently explain the
recent experimental observation of zero-energy end states in line defects of
monolayer Fe(Te,Se)/SrTiO$_3$ by scanning tunneling microscopy (STM)
measurements. Our research not only demonstrates an unprecedented interplay
among native line defect, emergent magnetism and topological superconductivity
but also explores a high-temperature platform for Majorana fermions.
