Images of edge current in InAs/GaSb quantum wells

Abstract

Quantum spin Hall devices with edges much longer than several microns do not display ballistic transport: that is, their measured conductances are much less than $e^2/h$ per edge. We imaged edge currents in InAs/GaSb quantum wells with long edges and determined an effective edge resistance. Surprisingly, although the effective edge resistance is much greater than $h/e^2$, it is independent of temperature up to 30 K within experimental resolution. Known candidate scattering mechanisms do not explain our observation of an effective edge resistance that is large yet temperature-independent.

Version accepted to Physical Review Letters (http://prl.aps.org/). 12 pages, 3 figures. Supplementary Online Materials available at http://stanford.edu/group/moler/papers/Spanton_InAsGaSb_imaging_SI_v2.pdf