Open AccessJournal Article
Observation of Majorana fermions in ferromagnetic atomic chains on a superconductor
TLDR
High-resolution spectroscopic imaging techniques show that the onset of superconductivity, which gaps the electronic density of states in the bulk of the Fe chains, is accompanied by the appearance of zero-energy end-states, providing strong evidence for the formation of a topological phase and edge-bound Majorana fermions in atomic chains.Abstract:
A possible sighting of Majorana states Nearly 80 years ago, the Italian physicist Ettore Majorana proposed the existence of an unusual type of particle that is its own antiparticle, the so-called Majorana fermion. The search for a free Majorana fermion has so far been unsuccessful, but bound Majorana-like collective excitations may exist in certain exotic superconductors. Nadj-Perge et al. created such a topological superconductor by depositing iron atoms onto the surface of superconducting lead, forming atomic chains (see the Perspective by Lee). They then used a scanning tunneling microscope to observe enhanced conductance at the ends of these chains at zero energy, where theory predicts Majorana states should appear. Science, this issue p. 602; see also p. 547 Scanning tunneling microscopy is used to observe signatures of Majorana states at the ends of iron atom chains. [Also see Perspective by Lee] Majorana fermions are predicted to localize at the edge of a topological superconductor, a state of matter that can form when a ferromagnetic system is placed in proximity to a conventional superconductor with strong spin-orbit interaction. With the goal of realizing a one-dimensional topological superconductor, we have fabricated ferromagnetic iron (Fe) atomic chains on the surface of superconducting lead (Pb). Using high-resolution spectroscopic imaging techniques, we show that the onset of superconductivity, which gaps the electronic density of states in the bulk of the Fe chains, is accompanied by the appearance of zero-energy end-states. This spatially resolved signature provides strong evidence, corroborated by other observations, for the formation of a topological phase and edge-bound Majorana fermions in our atomic chains.read more
Citations
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New perspectives for Rashba spin–orbit coupling
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Colloquium : Topological band theory
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Beyond Dirac and Weyl fermions: Unconventional quasiparticles in conventional crystals
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Topological superconductors: a review
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TL;DR: In this paper, the relation between topological superconductivity and Majorana fermions is explained, and the difference between dispersive Majorana Fermions and a localized Majorana zero mode is emphasized.
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Exponential protection of zero modes in Majorana islands
S. M. Albrecht,Andrew Higginbotham,Andrew Higginbotham,Morten Hannibal Madsen,Ferdinand Kuemmeth,Thomas Sand Jespersen,Jesper Nygård,Peter Krogstrup,Charles Marcus +8 more
TL;DR: The results help to explain the trivial-to-topological transition in finite systems and to quantify the scaling of topological protection with end-mode separation.
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Superconducting Proximity Effect and Majorana Fermions at the Surface of a Topological Insulator
Liang Fu,Charles L. Kane +1 more
TL;DR: It is shown that linear junctions between superconductors mediated by the topological insulator form a nonchiral one-dimensional wire for Majorana fermions, and that circuits formed from these junctions provide a method for creating, manipulating, and fusing Majorana bound states.
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