Increased localization of Majorana modes in antiferromagnetic chains on superconductors

Abstract

Magnet-superconductor hybrid (MSH) systems are a key platform for custom-designed topological superconductors. Ideally, the ends of a one-dimensional MSH structure will host Majorana zero-modes (MZMs), the fundamental unit of topological quantum computing. However, some of the experiments with ferromagnetic chains show a more complicated picture. Due to tiny gap sizes and hence long coherence lengths MZMs might hybridize and lose their topological protection. Recent experiments on a niobium surface have shown that both ferromagnetic and antiferromagnetic chains may be engineered, with the magnetic order depending on the crystallographic direction of the chain. While ferromagnetic chains are well understood, antiferromagnetic chains are less so. Here we study two models inspired by the niobium surface: a minimal model to elucidate the general topological properties of antiferromagnetic chains, and an extended model to more closely simulate a real system by mimicking the proximity effect. We find that in general for antiferromagnetic chains the topological gap is larger than for ferromagnetic ones and thus coherence lengths are shorter for antiferromagnetic chains, yielding more pronounced localization of MZMs in these chains. While topological phases for both ferromagnetic and antiferromagnetic chains both depend on the magnetic moment of the adatoms and the chemical potential, we find that antiferromagnetic chains also have a strong dependence on the magnitude of Rashba spin-orbit coupling at the surface.

12 pages,11 figures

References in corpus (26)

• Non-Abelian Anyons and Topological Quantum Computation
• Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices
• Majorana Fermions and a Topological Phase Transition in Semiconductor-Superconductor Heterostructures
• Classification of topological insulators and superconductors in three spatial dimensions
• Observation of Majorana Fermions in Ferromagnetic Atomic Chains on a Superconductor
• Observation of Majorana Fermions in a Nb-InSb Nanowire-Nb Hybrid Quantum Device
• Distinguishing a Majorana zero mode using spin resolved measurements
• Topological Superconductivity induced by Ferromagnetic Metal Chains
• Evidence of topological Shiba bands in artificial spin chains on superconductors
• Controlled length-dependent interaction of Majorana modes in Yu-Shiba-Rusinov chains
• Interplay of topological phases in magnetic adatom-chains on top of a Rashba superconducting surface
• Spin-orbit coupling induced splitting of Yu-Shiba-Rusinov states in antiferromagnetic dimers
• Atomic-scale spin-polarization maps using functionalized superconducting probes
• Controlling in-gap end states by linking nonmagnetic atoms and artificially-constructed spin chains on superconductors
• Quantized charge transport in chiral Majorana edge modes
• Phase diagram of a distorted kagome antiferromagnet and application to Y-kapellasite
• Observation of tunable single-atom Yu-Shiba-Rusinov states
• Non-Majorana modes in diluted spin chains proximitized to a superconductor
• Long range and highly tunable interaction between local spins coupled to a superconducting condensate
• Correlating Josephson supercurrents and Shiba states in quantum spins unconventionally coupled to superconductors
• Topological Superconductivity Induced by Magnetic Texture Crystals
• Coexistence of Antiferromagnetism and Superconductivity in Mn/Nb(110)
• High-Temperature Majorana Fermions in Magnet-Superconductor Hybrid Systems
• Majorana bound states in a superconducting Rashba nanowire in the presence of antiferromagnetic order
• Anomalous excitations of atomically crafted quantum magnets
• Complex magnetic ground states and topological electronic phases of atomic spin chains on superconductors

Cited by in corpus (5)

• Testing the topological nature of end states in antiferromagnetic atomic chains on superconductors
• Majorana quasiparticles in atomic spin chains on superconductors
• Topological superconductivity in Fibonacci quasicrystals
• Magnetic flux induced higher-order topological superconductivity
• Magnetic flux induced topological superconductivity in magnetic atomic rings