Please use this identifier to cite or link to this item: https://scholarbank.nus.edu.sg/handle/10635/155398
Title: Measuring valley polarization in transition metal dichalcogenides with second-harmonic spectroscopy
Authors: HO, YI WEI 
ROSA, HENRIQUE GUIMARAES 
VERZHBITSKIY, IVAN 
RODRIGUES, MANUEL JOSE DE LIMA FERREIRA 
TANIGUCHI, TAKASHI
WATANABE, KENJI
EDA, GOKI 
PEREIRA, VITOR MANUEL 
VIANA-GOMES, JOSE CARLOS 
Keywords: physics.optics
physics.optics
cond-mat.mtrl-sci
Issue Date: 4-Mar-2019
Citation: HO, YI WEI, ROSA, HENRIQUE GUIMARAES, VERZHBITSKIY, IVAN, RODRIGUES, MANUEL JOSE DE LIMA FERREIRA, TANIGUCHI, TAKASHI, WATANABE, KENJI, EDA, GOKI, PEREIRA, VITOR MANUEL, VIANA-GOMES, JOSE CARLOS (2019-03-04). Measuring valley polarization in transition metal dichalcogenides with second-harmonic spectroscopy. ScholarBank@NUS Repository.
Abstract: Inducing a population imbalance at different valleys of an electronic system lowers its effective rotational symmetry. We introduce a technique to measure such valley imbalance (a valley polarization) that directly exploits this symmetry reduction as well as the unique fingerprints it has in the polarization-dependent second-harmonic generation. We describe the principle and detection scheme in the context of hexagonal two-dimensional crystals, which include graphene-based systems and the family of transition metal dichalcogenides. The technique is demonstrated on a MoSe$_2$ monolayer at room temperature. We include a model that shows the valley polarization-induced second-harmonic susceptibility is proportional to the effective valley imbalance, and one order of magnitude larger for quasi-resonant pump conditions versus off-resonant excitation. Importantly, we deliberately keep the setup as simple as possible, where a single laser beam simultaneously creates a controllable valley imbalance and pumps the second-harmonic process. In addition to providing the first experimental demonstration of the effect, this work establishes a conceptually very simple and compact way of measuring the instantaneous valley polarization, with direct applicability in valleytronics.
URI: https://scholarbank.nus.edu.sg/handle/10635/155398
Appears in Collections:Staff Publications
Elements

Show full item record
Files in This Item:
File Description SizeFormatAccess SettingsVersion 
1903.01367v1.pdf1.13 MBAdobe PDF

OPEN

Post-printView/Download

Page view(s)

31
checked on Sep 5, 2019

Download(s)

1
checked on Sep 5, 2019

Google ScholarTM

Check


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.