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Mathieu Pierre: Quantum transport in few-layer WSe2 devices under high magnetic field

posted 6 Jul 2016, 02:13 by info admin
Mathieu Pierre, Nicolas Thiery, Bruno Camargo, Ming Yang, Michel Goiran and Walter Escoffier
Laboratoire national des champs magnétiques intenses (LNCMI), Université de Toulouse INSA UPS, CNRS, EMFL, FR-31400 Toulouse, France

We fabricated WSe2 devices in order to perform electronic transport measurements under high magnetic field. Few-layer flakes of WSe2 were deposited on h-BN flakes and electrically contacted with Pt/Au electrodes in a Hall bar configuration. We performed transport measurements under pulsed magnetic field up to 55T and at low temperature (4.2K). By applying a negative gate voltage to the substrate, we were able to investigate the hole conduction regime, despite non-ohmic contacts. Clear 1/B-periodic conductance oscillations appear above 20T. A single frequency is observed for low carrier density and additional features rise at large negative gate voltage. This effect is still under investigation. The transverse Hall voltage was simultaneously measured. We extract information on the carrier concentration as well as the valley and spin degeneracies. Our fabrication process allows to obtain devices with sufficient mobility to reach the quantum transport regime. Work is under progress to improve the device mobility and the ohmicity of the contacts. 

Mathieu Pierre is currently an assistant professor at the Laboratoire National des Champs Magnétiques Intenses (French high magnetic field laboratory). He graduated from École Normale Supérieure de Cachan with a M.Sc. in applied physics in 2007 and he received a Ph.D. from Grenoble University in 2010. His doctoral thesis was focused on single-electron effects and single-dopant transport in ultra-scaled silicon MOSFETs. Then, as a post-doctoral researcher in the Quantum Device Physics laboratory at Chalmers University of Technology in Sweden, he worked on tunable superconducting microwave resonators for circuit-QED experiments. He is now pursuing his research activity on quantum magneto-transport in nano-electronic devices.