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Eklund Lecture: Surface sensitive quantum interference in mesoscopic Bi2Se3

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Abhinav Kandala, Pennsylvania State University
20 March 2014 from 4:00 PM to 5:00 PM
117 Osmond Laboratory
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Studies of the quantum interference of electrons in condensed matter physics have typically used exquisite nanoscale patterning to steer electron waves. However, material systems with a self-organized structure of electron scattering centers could also provide a novel and unique platform for such studies. A promising candidate material is Bi2Se3 - a popular thermoelectric of the Bi chalcogenide family and a narrow band-gap semiconductor, which displays a correlated surface structure of nanoscale triangular terraces when grown by molecular beam epitaxy. In this context, we study magneto-transport in mesoscopic channels patterned “top-down” from epitaxial thin films of Bi2Se3. Our measurements on diffusive, straight channel devices reveal periodic conductance fluctuations seen previously only in explicitly patterned Aharanov-Bohm rings, and ballistic nanostructures.  By employing atomic force microscopy, we show that the characteristic area derived from the periodic fluctuations compares well with the typical terrace size at the surface. This suggests that scattering off the step edges creates dominant Aharonov-Bohm electronic orbits in the triangular terraces. Furthermore, the Bi chalcogenides have also attracted great attention as candidate topological insulators. I shall present our experiments with quantum interference as we magnetically dope and access the topological surface states in these systems.


[1] A. Kandala, A. Richardella, D. M. Zhang, T. Flanagan and N. Samarth, Nano Letters 13, 2471(2013).