PT  - JOURNAL ARTICLE
AU  - Nadj-Perge, Stevan
AU  - Drozdov, Ilya K.
AU  - Li, Jian
AU  - Chen, Hua
AU  - Jeon, Sangjun
AU  - Seo, Jungpil
AU  - MacDonald, Allan H.
AU  - Bernevig, B. Andrei
AU  - Yazdani, Ali
TI  - Observation of Majorana fermions in ferromagnetic atomic chains on a superconductor
AID  - 10.1126/science.1259327
DP  - 2014 Oct 31
TA  - Science
PG  - 602--607
VI  - 346
IP  - 6209
4099  - http://science.sciencemag.org/content/346/6209/602.short
4100  - http://science.sciencemag.org/content/346/6209/602.full
SO  - Science2014 Oct 31; 346
AB  - 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. 547Majorana 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.