"Measuring and controlling electric conductivity through a single atom" by Itai Keren and Prof. Hadar Steinberg

July 22, 2020
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Recent work by Itai Keren (a Ph.D student at Prof. Hadar Steinberg's group) along with co-authors provides a method to produce a transistor from a single atom. The article was published in Nature Communications under the title "Quantum Dot Assisted Spectroscopy of Degeneracy Lifted Landau Levels in Graphene” (For the full paper see here) and also presented in Ynet.

In their work the authors demonstrate the use a single defect in a tunnel barrier as a highly sensitive spectrometer. The experimental system is based on a van-der-Waals (vdW) graphite-graphene tunnel junction consisting of a 5 layer hexagonal Boron Nitride (hBN) tunnel barrier. The key element in our method is the use of defects, hosted in the barrier, as atomic-sized spectral probes. We show that dot-assisted transport provides sharp, stable spectral features found when the dot energy is resonant with the energies in the graphene. We measure graphene Landau level spectra up to 33 T and find a clear signature degeneracy lifting.

Defect dots are atomically sized and reside about 1 nm away from the graphene layer. As a result, the dot tunnel-couples to local regions. At the same time, unlike metallic tips used in STM, the dot cannot undergo spatial charge rearrangements and hence does not screen interactions on the local scale. In this sense, the dot can be considered as a “minimally invasive” probe.​

Defect dots are atomically sized and reside about 1 nm away from the graphene layer. As a result, the dot tunnel-couples to local regions. At the same time, unlike metallic tips used in STM, the dot cannot undergo spatial charge rearrangements and hence does not screen interactions on the local scale. In this sense, the dot can be considered as a “minimally invasive” probe.

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