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arXiv · 1308.6108

Majorana states in helical Shiba chains and ladders

Kim Pöyhönen·Alex Westström·Joel Röntynen·Teemu Ojanen
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Abstract

Motivated by recent proposals to realize Majorana bound states in chains and arrays of magnetic atoms deposited on top of a superconductor, we study the topological properties of various chain structures, ladders and two-dimensional arrangements exhibiting magnetic helices. We show that magnetic domain walls where the chirality of a magnetic helix is inverted support two protected Majorana states giving rise to a tunneling conductance peak twice the height of a single Majorana state. The topological properties of coupled chains exhibit nontrivial behaviour as a function of the number of chains beyond the even-odd dichotomy expected from the simple $\mathbb{Z}_2$ nature of coupled Majorana states. In addition, it is possible that a ladder of two or more coupled chains exhibit Majorana edge states even when decoupled chains are trivial. We formulate a general criterion for the number of Majorana edge states in multichain ladders and discuss some experimental consequences of our findings.

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Kim Pöyhönen, Alex Westström, Joel Röntynen, Teemu Ojanen. 2013-08-28. Majorana states in helical Shiba chains and ladders. https://doi.org/10.1103/physrevb.89.115109

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