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R. G. Herb Condensed Matter Seminar
Manipulating Valley Degree of Freedom via Nano-gating and Twist
Date: Thursday, September 25th
Time: 10:00 am - 6:00 pm
Place: 5310 Chamberlin
Speaker: Ke Wang, UMN
Abstract: Within condensed matter physics, the study of two-dimensional (2D) systems is a diverse and active field of interest with a rich history. High-quality two-dimensional electron gases (2DEG) in GaAs/AlGaAs heterostructures have enabled the discovery of rich quantum Hall physics. With the help of electron-beam-defined nano gates, system dimensions can be further reduced to be mesoscopic and comparable to the electron wavelength. In such gate-defined nanostructures, novel quantum phases can be locally defined and coherently manipulated to realize quantum bits and quantum interferometers, providing versatile experimental platforms to answer many key questions in condensed matter physics.

Since the discovery of graphene via mechanical exfoliation, it has been shown that the electronic properties of solids can undergo dramatic changes when the material thickness is reduced to the atomic limit. Moreover, the properties of the 2D materials can be further tailored by stacking them with relative twist angles. Combining this designer material platform with the gate-defined nanostructures, the highly tunable local Hamiltonian allows a local probe to the rich underlying physics and a platform to study new mesoscopic quantum phenomena. In this talk, I will discuss our recent experiments in tuning valley-specific Berry curvature and band topology in bilayer graphene via gate-defined nanostructures and twist, towards investigating novel mesoscopic quantum physics and demonstrating new quantum device concepts.
Host: TIANCHENG SONG
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