University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Wednesday, February 22nd 2017
1:25 pm:
Speaker: Ke Wang, Harvard University
Subject: Manipulating Charge Carriers for Quantum Transport in Van der Waals Materials Nanostructures
Candidate for the Condensed Matter Experimental Assistant Professor Position

Since the discovery of graphene via mechanical exfoliation, it has been shown that the electronic properties of solids can undergo dramatic change when the material thickness is reduced to the atomic limit. Recently, the quality of these 2-dimensional (2D) electronic systems has been significantly improved by hexagonal boron nitrides encapsulation, enabling the electron mean free path only limited by the size of the samples. However, mesoscopic transport studies in these systems are relatively unexplored due to the challenges in the device fabrication processes. Here we develop a robust procedure for making gated-defined nanostructures in 2D van der Waals materials without compromising their intrinsic 2DEG quality, providing versatile experimental platforms to explore various novel quantum phenomena in these systems. By confining and manipulating charge carriers [1][2], we demonstrate relativistic electron-optics, resonant quantum Hall (QH) tunneling spectroscopy, tunable optical trion lifetime and quantized mesoscopic transport in graphene and transition metal dichalcogenides [2]. Our results bode well for addressing many key problems in condensed matter physics, including Luttinger physics, high fidelity logic gates in Loss-DiVincenzo qubits, gate-controlled quantum optics, measurement of small fractional QH energy gaps, and functional quantum devices based on pseudospin manipulation and electron optics.

[1] Wang, et al, Phys. Rev. Lett. 111, 046801 (2013).
[2] Wang, et al, ArXiv:1610.02929 (2016).

Faculty Host: James Kakalios

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