Brian Dellabetta, Taylor L. Hughes, Matthew J. Gilbert, Benjamin L. Lev
Ultracold and quantum degenerate gases held near conductive surfaces can
serve as sensitive, high resolution, and wide-area probes of electronic current
flow. Previous work has imaged transport around grain boundaries in a gold wire
by using ultracold and Bose-Einstein condensed atoms held microns from the
surface with an atom chip trap. We show that atom chip microscopy may be
applied to useful purpose in the context of materials exhibiting topologically
protected surface transport. Current flow through lithographically tailored
surface defects in topological insulators (TI)---both idealized and with the
band-structure and conductivity typical of Bi_2Se_3---is numerically
calculated. We propose that imaging current flow patterns enables the
differentiation of an ideal TI from one with a finite bulk--to--surface
conductivity ratio, and specifically, that the determination of this ratio may
be possible by imaging transport around trenches etched into the TI's surface.
View original:
http://arxiv.org/abs/1202.0060
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