Topological orders competing for the Dirac surface state in FeSeTe surfaces

Abstract

FeSeTe has recently emerged as a leading candidate material for the two-dimensional topological superconductivity (TSC). Two reasons for the excitement are the high $T_c$ of the system and the fact that the Majorana zero modes (MZMs) inside the vortex cores live on the exposed surface rather than at the interface of a heterostructure as in the proximitized topological insulators. However, the recent scanning tunneling spectroscopy data have shown that, contrary to the theoretical expectation, the MZM does not exist inside every vortex core. Hence there are ``full'' vortices with MZMs and ``empty'' vortices without MZMs. Moreover the fraction of ``empty'' vortices increase with an increase in the magnetic field. We propose the possibility of two distinct gapped states competing for the topological surface states in FeSeTe: the TSC and half quantum anomalous Hall (hQAH). The latter is promoted by magnetic field through the alignment of magnetic impurities such as Fe interstitials. When hQAH takes over the topological surface state, the surface will become transparent to scanning tunneling microscopy and the nature of the vortex in such region will appear identical to what is expected of the vortices in the bulk, i.e., empty. Unmistakable signature of the proposed mechanism for empty vortices will be the existance of chiral Majorana modes(CMM) at the domain wall between a hQAH region and a TSC region. Such CMM should be observable by observing local density of states along a line connecting an empty vortex to a nearby full vortex.

6 pages, 4 figures + supplementary materials

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• Observation and characterization of the zero energy conductance peak in the vortex core state of FeTe${}_{0.55}$Se${}_{0.45}$

Cited by in corpus (13)

• On the Remarkable Superconductivity of FeSe and its Close Cousins
• Interface-Induced Superconductivity in Magnetic Topological Insulator-Iron Chalcogenide Heterostructures
• Vortex-line topology in iron-based superconductors with and without second-order topology
• Emergent vortex Majorana zero mode in iron-based superconductors
• Surface Bogoliubov-Dirac cones and helical Majorana hinge modes in superconducting Dirac semimetals
• Origin of Topological Surface Superconductivity in FeSe${}_{0.45}$Te${}_{0.55}$
• Ferromagnetic Impurity Induced Majorana Zero Mode in Iron-Based Superconductor
• Competing topological superconducting phases in FeSe${}_{0.45}$Te${}_{0.55}$
• On the signatures of non-topological patches on the surface of topological insulators
• Stealth Majorana Zero Mode in a Trilayer Heterostructure MnTe/Bi2Te3/Fe(Te,Se)
• Controllable Majorana vortex states in iron-based superconducting nanowires
• Double Majorana Vortex Flat Bands in the Topological Dirac Superconductor
• Majorana vortex phases in time-reversal invariant higher-order topological insulators and topologically trivial insulators