ABC...z Seminar Series: Thursday,April 5th: Imaging interaction effects in semiconducting nanowires

Event Date: 

Thursday, April 5, 2018 - 3:45pm

Event Date Details: 

Refreshments served at 3:30pm.

Event Location: 

  • Elings Hall 1605
  • ABC...z Seminar Series

Electrons confined to one dimension exhibit various counter-intuitive phenomena such as charge fractionalization, spin-charge separation, and Majorana end modes induced at nanowires rendered topologically superconducting.  We study semiconducting InAs nanowires in scanning tunnelling spectroscopy. By maintaining the MBE grown nanowires under ultra-high vacuum we are able to atomically resolve their facets and spectroscopically investigate their quasi-one-dimensional electronic states.

We find a non-monotonic energy evolution of the phase coherence of hot electrons in one dimension [1]. Above a certain energy threshold the higher the initial energy of the hot electron is, the more stable it becomes against decoherence, defying Landau’s paradigm. A theoretical model reveals that the origin of this unique energy-evolution of phase coherence lies in the form of the Coulomb interaction in one-dimension together with the non-linear electronic dispersion.

We further study superconducting (aluminium) quantum dots grown epitaxially on the InAs nanowires. The barrier at the Al/InAs interface along with the tip of the STM form a double barrier tunnelling junction, featuring Coulomb gap and charging resonances. This regime allows us to probe the buried Al/InAs interface through the displacement current. Its potential for measurements of topological superconductivity will be discussed.

Finally, a self-tuned method of adiabatic transportation of Majorana end modes will be shown. It supports scalable single gate braiding operation.

Figure 1: Topographic image of two InAs nanowires on a gold substrate imaged in a scanning tunnelling microscope. The inset shows the atomically resolved {11-20} side facet of the Wurzite nanowire grown along the <0001> direction.

Haim Beidenkopf, Weizmann Institute of Science