Research

VALLEYHALL: Towards the Valley Hall effect in monolayer MoS2: Magneto-optics, transport and theory

Research project selected under the 2012 call for proposals

Principal Investigator :

Bernhard Urbaszek (urbaszek@insa-toulouse.fr)
LPCNO (Quantum Optoelectronics Group (OPTO))

Type of project : Collaborative Project

Partner team(s) :

LNCMI

LPCNO (Modeling in Physics and Chemistry (MPC))

Date (start/end) : 2013 - 2015

Valley dynamics in one atomic monolayer of WSe2 is investigated in time resolved optical spectroscopy, one of the key targets of the Valleyhall project.

Abstract

Monolayer MoS2 has emerged as a very promising material for optoelectronic and spin-based applications for two reasons: (1) the indirect bulk semiconductor MoS2 becomes direct when thinned to one monolayer, resulting in efficient optical absorption and emission. (2) the inherent inversion symmetry breaking (usually absent in graphene) together with the strong spin-orbit interaction leads to a coupling of carrier spin and kspace valley physics. The aim of this project is to bring together the expertise of the LPCNO and the LNCMI that cover all competences necessary for a first demonstration of the Valley Hall effect: Sample material will be fabricated through micromechanical cleavage, monolayer regions will be identified through in-house microcharacterization.
The intervalley scattering times will be quantified in time-resolved micro-photoluminescence.
Combined with the conductivity and effective mass determination in strong applied magnetic fields (Shubinkovde Hass Oscillations), this paves the way for original photo-induced Valley Hall and Spin Hall experiments, with strong support from theory to optimize the choice of substrates and dopants.

 

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