Center for Artificial Low Dimensional Electronic Systems

Spin polarization measurement of ferromagnetic atomic chains on a superconductor

Sangjun Jeon

April 29(Fri) - April 29(Fri), 2016

Spin polarization measurement of

ferromagnetic atomic chains on a superconductor

Sangjun Jeon¹, Yonglong Xie¹, Ilya K. Drozdov^1§, Jian Li¹,

B. Andrei Bernevig¹, and Ali Yazdani­¹

¹Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08544, USA

^§present address: Brookhaven National Laboratory, Upton, NY 11973, USA

A key property of the Majorana fermions edge mode when realized at the edge of a topological superconductor is their spin. Unlike other low energy excitation in a conventional superconductor, which are made up of time-reverse partners of up and down spin, Majorana is expected to have a definite spin orientation. Chains of magnetic atoms in close proximity to the superconductor with spin-orbit coupling has been proposed as a platform for 1D topological superconductivity¹. The experimental observation of zero energy peak which is localized to the end of the chain is well described by the Majorana quasi particle bound states formed at the end of non-trivial superconducting chain¹. While this previous study shows evidences of ferromagnetism and spin-orbit coupling in such atomic chains on Pb which are the key ingredients to hold the topological superconductivity, the spin properties of the zero energy end mode have not been explored. Here, we introduce the technique of spin polarized scanning tunneling microscopy and spectroscopy (SP-STM) combined with an external magnet to orient the tip magnetization. We utilize this technique to resolve the spin polarization of the zero energy excitation induced by the Fe atomic chains grown on the Pb(110) surface.

1.     S. Nadj-Perge, I.K. Drozdov, J. Li, H. Chen, S. Jeon, J. Seo, A.H. Macdonald, B.A. Bernevig, A. Yazdani, “Observation of Majoran fermions in ferromagnetic atomic chains on a superconductor”, Science, 346, 602, 2014