Effect of Zeeman coupling on the Majorana vortex modes in iron-based topological superconductors

Areg Ghazaryan, P. L.S. Lopes, Pavan Hosur, Matthew J. Gilbert, Pouyan Ghaemi

Research output: Contribution to journalArticlepeer-review

Abstract

In the superconducting regime of FeTe(1-x)Sex, there exist two types of vortices which are distinguished by the presence or absence of zero-energy states in their core. To understand their origin, we examine the interplay of Zeeman coupling and superconducting pairings in three-dimensional metals with band inversion. Weak Zeeman fields are found to suppress intraorbital spin-singlet pairing, known to localize the states at the ends of the vortices on the surface. On the other hand, an orbital-triplet pairing is shown to be stable against Zeeman interactions, but leads to delocalized zero-energy Majorana modes which extend through the vortex. In contrast, the finite-energy vortex modes remain localized at the vortex ends even when the pairing is of orbital-triplet form. Phenomenologically, this manifests as an observed disappearance of zero-bias peaks within the cores of topological vortices upon an increase of the applied magnetic field. The presence of magnetic impurities in FeTe(1-x)Sex, which are attracted to the vortices, would lead to such Zeeman-induced delocalization of Majorana modes in a fraction of vortices that capture a large enough number of magnetic impurities. Our results provide an explanation for the dichotomy between topological and nontopological vortices recently observed in FeTe(1-x)Sex.

Original languageEnglish (US)
Article number020504
JournalPhysical Review B
Volume101
Issue number2
DOIs
StatePublished - Jan 13 2020

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Fingerprint Dive into the research topics of 'Effect of Zeeman coupling on the Majorana vortex modes in iron-based topological superconductors'. Together they form a unique fingerprint.

Cite this