Quantum Transport and Electron Interactions in Few-Layer Atomic Membranes

报告人: Chun Ning (Jeanie) Lau (Department of Physics and Astronomy at University of California, Riverside)

报告时间: 2016年6月28日 16:00

报告地点: 理科楼三楼报告厅(C302)

摘要:Two dimensional materials constitute an exciting and unusually tunable platform for investigation of both fundamental phenomena and electronic applications. Here I will present our results on transport measurements on high mobility few-layer graphene and phosphorene devices. In bilayer and trilayer graphene devices with mobility as high as 400,000 cm2/V, we observe intrinsic gapped states at the charge neutrality point, arising from electronic interactions. This state is identified to be a layer antiferromagnetic state with broken time reversal symmetry. In another few-layer graphene system, ABA-stacked trilayer graphene consists of multiple Dirac bands, where crystal symmetry protects the spin degenerate counter-propagating edge modes resulting in σxx = 4e2/h. At even higher magnetic fields, the crystal symmetry is broken in by electron-electron interactions and the =0 quantum Hall state develops an insulating phase with non-monotonic dependence on temperature and magnetic field. Our findings indicate the role of crystal and spin symmetry in generation of topological phases in multiple Dirac bands. At finite doping, we explore the tunable integer and fractional quantum Hall states and Landau level crossings in these few-layer systems. Finally, I will present our recent results on quantum oscillations and weak localization in air-stable, few-layer phosphorene devices. Our results underscore the fascinating many-body physics in these 2D membranes.

个人简介:Chun Ning (Jeanie) Lau is a Professor in the Department of Physics and Astronomy at University of California, Riverside. She received BA in physics from University of Chicago in 1994, and PhD in physics from Harvard in 2001. She was a research associate at Hewlett Packard Labs in Palo Alto from 2002 to 2004, before joining UCR in 2004 as an assistant professor. She was promoted to associate professor in 2009 and full professor in 2012. Her research focuses on electronic, thermal and mechanical properties of nanoscale systems, in particular, graphene and other two-dimensional systems. She has published more than 80 papers and given more than 100 invited talks worldwide. She is the recipient of the NSF CAREER award and the PECASE award (Presidential Early Career Award for Scientists and Engineers), the highest honor bestowed to scientists and engineers at the early stage of their careers. She served on the editorial board of 2D Materials (2014-2015) and is currently an Associate Editor of Nano Letters.