Studying topological phases of matter in reduced dimensions under the scanning tunneling microscope

Abstract

Condensed matter physics has experienced a recent boom in the search for topological phases of matter with exploration of material systems that possess topological properties and promise applications in spintronics and quantum computing. Topological systems in reduced dimension are of particular interest as they can possess topologically non-trivial boundary states while potentially being compact in size. 2D and 1D topological systems, however, have been far less experimentally studied as compared to their 3D counterparts. In this thesis direct spectroscopic evidence from Scanning Tunneling Microscopy (STM) experiments for topological edge states will be presented for the two topological phases: (i) a 2D topological insulator (quantum spin Hall) phase realized in a system of Bismuth bilayers and (ii) 1D topological superconductor phase in a synthetic system of ferromagnetic chains on an s-wave superconductor. The end states of the later system are believed to be a realization of Majorana fermions in solid state.