Majorana Bound States Induced by Antiferromagnetic Skyrmion Textures

Abstract

Majorana bound states are zero-energy states predicted to emerge in topological superconductors and intense efforts seeking a definitive proof of their observation are still ongoing. A standard route to realize them involves antagonistic orders: a superconductor in proximity to a ferromagnet. Here we show this issue can be resolved using antiferromagnetic rather than ferromagnetic order. We propose to use a chain of antiferromagnetic skyrmions, in an otherwise collinear antiferromagnet, coupled to a bulk conventional superconductor as a novel platform capable of supporting Majorana bound states that are robust against disorder. Crucially, the collinear antiferromagnetic region neither suppresses superconductivity nor induces topological superconductivity, thus allowing for Majorana bound states localized at the ends of the chain. Our model introduces a new class of systems where topological superconductivity can be induced by editing antiferromagnetic textures rather than locally tuning material parameters, opening avenues for the conclusive observation of Majorana bound states.

Majorana Braiding Racetracks from Charge Chern Insulator - Superconductor Hybrids

“…Our braiding protocol in MZM racetracks relies on the MZM track exchange, which is a process that allows pairs of MZMs to simultaneously swap track. In contrast to prior works which have discussed the spatial exchange of a MZM pair by means of T-junctions [81], Yjunctions [111], or skyrmion-based racetracks [112], here the braiding transformation stems solely from the MZM track exchange. As we show in this work, additional processes which shuttle the MZMs in the racetrack in order to complete the MZM exchange, do not contribute to the non-Abelian part of the Berry phase picked up by the twofold-degenerate ground state of the system.…”

Majorana bound states in semiconducting nanostructures

“…We note that even more complicated non-collinear magnetic textures, such as skyrmions or skyrmion chains, were proposed as an alternative route to generate topological superconducting phases. [157][158][159][160][161][162][163][164][165][166][167] Alternatively, we note that external driving provides a powerful tool to turn initially nontopological materials into topological ones. 128,129 Indeed, it has been shown that a time-dependent magnetic or electric field can give rise to Floquet Majorana fermions.…”

Aspects of topological superconductivity in 2D systems: noncollinear magnetism, skyrmions, and higher-order topology

“…Another way to create superconductor / noncollinear magnet bilayers hosting magnetic excitations with a large topological index Q is to consider skyrmion lattices, ribbons or chains with the proximity-induced superconductivity, Refs. [36,174]. In Ref.…”

“…skyrmion chains, were considered in Ref. [174]. To avoid the problem of the suppression of superconductivity by ferromagnetic correlations, an antiferromagnetic skyrmion chain (ASC) was considered, see Fig.…”