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Momentum-Resolved Spectroscopic Imaging of Dirac Fermions in Topological Materials

Speaker: 
Anjan Soumyanarayanan (Harvard University & MIT, USA)
Date: 
Wed, 23/01/2013 - 11:00am to 12:00pm
Location: 
S13-02-14 (Physics Resource Room, NUS)
Event Type: 
Seminars

Abstract

The last four years have witnessed the emergence of a new class of electronic materials whose properties are determined by the mathematical notion of topology. These `topological materials’ host surface states that mimic spin-polarized Dirac particles and are expected to be insensitive to material disorder. To harness the properties of these surface states and develop topological materials towards spin-based applications, it is crucial to understand and quantify their behavior on the nanoscale.

Using scanning tunneling microscopy (STM), we visualize surface state Dirac fermions in antimony, and report the first simultaneous observation of Landau quantization and quasiparticle interference in any material. We establish the spectroscopic equivalence of these two momentum-resolved phenomena, and combine them to quantitatively reconstruct the surface state band structure. We use our observations to quantify the robustness of surface states to disorder, thereby informing the development of new topological materials. We further examine the spectroscopic effects of single atom impurities on the surface states.

 

 

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