# Applied Physics Seminar

**Majorana Fermions in Chains of Magnetic Atoms on a superconductor**

**Speaker:**Stevan Nadj-Perge, Department of Physics, Princeton University

**Location:**Watson 104

Majorana fermions are zero energy excitations predicted to exist on the edges of topological superconductors. Due to their non-abelian nature they are considered as potential building blocks of a topological quantum computer.

In this talk, I will present novel experimental approach to realize Majorana fermions in a chain of magnetic atoms placed on the surface of a usual (topologically trivial) superconductor. Our experimental efforts are motivated by model calculations which show that such chains can support topological superconductivity with Majorana end modes [1]. Surprisingly, we find that even short chains consisting of tens of atoms can host well resolved Majorana modes under suitable conditions depending on the relative spin orientations of adjacent atoms. We have realized magnetic chains using self-assembled growth technique and probed their electronic structure using scanning tunneling microscopy. Results from spatially resolved spectroscopic mapping reveal zero energy modes at the chain ends [2]. I will discuss the possible origin of the observed zero-bias peaks in the context of Majorana bound states and other recently proposed alternatives. In the end, I will give a brief outlook for this line of research.

[1] S. Nadj-Perge, I. K. Drozdov, B. A. Bernevig., Ali Yazdani, Phys. Rev. B **88**, 020407(R) (2013).

[2] S. Nadj-Perge, I. K. Drozdov, S. Jeon, J. Seo, B. A. Bernevig, Ali Yazdani*,* (in preparation).

**More about the speaker: **Stevan Nadj-Perge is a Postdoctoral Researcher at Princeton University. He received his MS in Theoretical Physics from the University of Belgrade, Serbia in 2005 and a PhD in Applied Physics from Delft University in 2010. His research interests include engineered topological systems and materials (such as topological insulators, topological crystalline insulators and two dimensional quantum spin hall states) and their possible applications in nanoscience with the emphasis on realizing Majorana fermions, topological zero-energy excitations and coherent spin control in semiconducting nanostructures.

**Series**Applied Physics Seminar Series

**Contact:** Michelle Aldecua at 3982 maldecua@caltech.edu