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Seminar 11/13/2013 - Emanuel Tutuc, University of Texas at Austin: Electron Transport in Atomic Layer Heterostructures

Abstract: Recent years have witnessed an increased interest in atomic layer semiconductors, such as graphene and transition metal dichalcogenides.  These semiconductors possess unique properties such as massless fermions in graphene mononolayer, tunable band-gap in graphene bilayers, or large effective mass (~0.5me) in transition metal dichalcogenide layers.  In this presentation we discuss the realization of atomic layer heterostructures using a layer-by-layer transfer approach, and a set of electron transport experiments aimed at probing the electron-electron interaction in graphene and MoS2.     

Using graphene double layers consisting of two graphene layers separated by a thin dielectric, we probe the frictional drag resulting from the inter-layer interaction, as a function of layer densities and temperature, and discuss the results in the context of existing theoretical studies.

A second topic discussed in this presentation is a technique that allows a direct measurement of the Fermi energy in an electron system, using a double layer heterostructure.  The underlying principle of the technique is that an interlayer bias applied to maintain one of the layers at charge neutrality is equal to the Fermi energy of the opposite layer. Using this technique we probe the Fermi energy in monolayer and bilayer graphene as a function of density, and identify the band structure and exchange-correlation contributions to the Fermi energy. 

Using graphene double layers with high layer mobility, we investigate the quantum Hall (QH) effect in high magnetic fields. We discuss the interplay between spin and valley degree of freedom which leads to spin or valley polarized QH states in high magnetic fields, and examine the transitions from spin-to-valley polarized as a function of filling factor and transverse electric field. 

Bio: Emanuel Tutuc is an Associate Professor in the Electrical & Computer Engineering department at The University of Texas at Austin. He received the B.S. degree in Physics from Ecole Normale Supérieure, University of Paris, and Ph.D. in Physics from Princeton University. From 2004 to 2006 he was a post-doctoral researcher at I.B.M. T.J. Watson Research Center. He joined the faculty of The University of Texas at Austin within the Department of Electrical Engineering and the Microelectronics Research Center in the spring of 2007. His current research is centered on the electronic properties of atomic layer heterostructures and semiconductor nanowires, novel devices, and chemical vapor deposition. Prof. Tutuc has received a DARPA Young Faculty Award in 2008, and a National Science Foundation CAREER award in 2009.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Location: Bowen Hall Auditorium

Date/Time: 11/13/13 at 12:00 pm - 11/13/13 at 1:00 pm

Category: PRISM/PCCM Seminar Series

Department: PRISM