Influence of disorder on antidot vortex Majorana states in 3D topological insulators

Abstract

Topological insulator/superconductor two-dimensional heterostructures are promising candidates for realizing topological superconductivity and Majorana modes. In these systems, a vortex pinned by a pre-fabricated antidot in the superconductor can host Majorana zero-energy modes (MZMs), which are exotic quasiparticles that may enable quantum information processing. However, a major challenge is to design devices that can manipulate the information encoded in these MZMs. One of the key factors is to create small and clean antidots, so the MZMs, localized in the vortex core, have a large gap to other excitations. If the antidot is too large or too disordered, the level spacing for the subgap vortex states may become smaller than temperature. In this paper, we numerically investigate the effects of disorder, chemical potential, and antidot size on the subgap vortex spectrum, using a two-dimensional effective model of the topological insulator surface. Our model allows us to simulate large system sizes with vortices up to 1.8 $\mu$m in diameter (with a 6 nm lattice constant). We also compare our disorder model with the transport data from existing experiments. We find that the spectral gap can exhibit a non-monotonic behavior as a function of disorder strength, and that it can be tuned by applying a gate voltage.

17 pages, 11 figures

References in corpus (11)

• Non-Abelian Anyons and Topological Quantum Computation
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Majorana Fermions and a Topological Phase Transition in Semiconductor-Superconductor Heterostructures
• Observation of topological surface state quantum Hall effect in an intrinsic three-dimensional topological insulator
• InAs-Al Hybrid Devices Passing the Topological Gap Protocol
• Non-sinusoidal current-phase relationship in Josephson junctions from the 3D topological insulator HgTe
• Signatures of a topological phase transition in a planar Josephson junction
• Majorana state on the surface of a disordered 3D topological insulator
• Fractional AC Josephson effect in a topological insulator proximitized by a self-formed superconductor
• Statistical Majorana Bound State Spectroscopy
• Finite temperature effects on Majorana bound states in chiral $p$-wave superconductors

Cited by in corpus (2)

• Detection of Majorana zero modes bound to Josephson vortices in planar superconductor-topological insulator-superconductor junctions
• Unveiling In-Gap States and Majorana Zero Modes in Superconductor-Topological Insulator Bilayer model