# Optical Investigation of Monolayer and Bulk Tungsten Diselenide (WSe₂) in High Magnetic Fields.

@article{Mitioglu2015OpticalIO,
title={Optical Investigation of Monolayer and Bulk Tungsten Diselenide (WSe₂) in High Magnetic Fields.},
author={A A Mitioglu and Paulina Płochocka and Andr{\'e}s Granados del {\'A}guila and Peter C M Christianen and George Deligeorgis and Sergiu Anghel and Leonid Kulyuk and Duncan K. Maude},
journal={Nano letters},
year={2015},
volume={15 7},
pages={
4387-92
}
}
• Published 12 June 2015
• Physics
• Nano letters
Optical spectroscopy in high magnetic fields B ≤ 65 T is used to reveal the very different nature of carriers in monolayer and bulk transition metal dichalcogenides. In monolayer WSe2, the exciton emission shifts linearly with the magnetic field and exhibits a splitting that originates from the magnetic field induced valley splitting. The monolayer data can be described using a single particle picture with a Dirac-like Hamiltonian for massive Dirac Fermions, with an additional term to…
77 Citations

## Figures from this paper

Excitonic Valley Effects in Monolayer WS2 under High Magnetic Fields.
• Physics
Nano letters
• 2016
A monolayer of tungsten disulfide in high magnetic fields up to 30 T via photoluminescence spectroscopy at low temperatures is investigated and the field dependence of the trion valley polarizations is in line with the predicted trion splitting into singlet and triplet configurations.
The Zeeman splitting of bulk 2H-MoTe2 single crystal in high magnetic field
• Physics
• 2017
A high magnetic field magneto-optical spectrum is utilized to study the A exciton of bulk 2H-MoTe2 single crystal. A clear Zeeman splitting of the A exciton is observed under high magnetic fields up
Magnetoreflection spectroscopy of monolayer transition-metal dichalcogenide semiconductors in pulsed magnetic fields
• Physics
• 2016
The authors describe recent experimental efforts to perform polarization-resolved optical spectroscopy of monolayer transition-metal dichalcogenide semiconductors in very large pulsed magnetic fields
Zeeman Splitting and Inverted Polarization of Biexciton Emission in Monolayer WS_{2}.
• Physics
Physical review letters
• 2018
This work studies the magnetic-field-induced splitting of biexcitons in monolayer WS_{2} using polarization-resolved photoluminescence spectroscopy in out-of-plane magnetic fields up to 30 T, revealing the critical role of dark exciton in the composition of this many-body state.
Exciton diamagnetic shifts and valley Zeeman effects in monolayer WS2 and MoS2 to 65 Tesla
• Physics
Nature communications
• 2016
Low-temperature polarized reflection spectroscopy of atomically thin WS2 and MoS2 in high magnetic fields to 65 T is reported, thereby quantifying the valley Zeeman effect in monolayer transition-metal disulphides.
Magneto photoluminescence measurements of tungsten disulphide monolayers.
• Physics
Journal of physics. Condensed matter : an Institute of Physics journal
• 2017
Photoluminescence measurements of CVD-grown tungsten disulphide (WS2) monolayers at temperatures of 2 K are presented and by applying magnetic fields up to 7 T in Faraday geometry, a splitting of the photolumscence peaks can be observed.
Tuning Valley Polarization in a WSe 2 Monolayer with a Tiny Magnetic Field
• Physics
• 2016
In monolayers of semiconducting transition metal dichalcogenides, the light helicity ($\sigma^+$ or $\sigma^-$) is locked to the valley degree of freedom, leading to the possibility of optical
Spatial extent of the excited exciton states in WS2 monolayers from diamagnetic shifts
• Physics
Physical Review B
• 2018
We experimentally study the radii of excitons in hBN-encapsulated WS2 monolayers by means of magneto-optical reflectance spectroscopy at cryogenic temperatures in magnetic fields up to 29 T. We
Orbital magneto-optical response of periodic insulators from first principles
• Physics
npj Computational Materials
• 2019
Magneto-optical response, i.e. optical response in the presence of a magnetic field, is commonly used for characterization of materials and in optical communications. However, quantum mechanical
Magnetooptics of Exciton Rydberg States in a Monolayer Semiconductor.
• Physics
Physical review letters
• 2018
The strongly field-dependent and distinct energy shifts of the 2s, 3s, and 4s excited neutral excitons permits their unambiguous identification and allows for quantitative comparison with leading theoretical models.

## References

SHOWING 1-10 OF 36 REFERENCES
Breaking of valley degeneracy by magnetic field in monolayer MoSe2.
• Physics
Physical review letters
• 2015
Using polarization-resolved photoluminescence spectroscopy, the breaking of valley degeneracy by an out-of-plane magnetic field in back-gated monolayer MoSe2 devices is investigated and the luminescence handedness can be controlled with a magnetic field to a degree that depends on the back-gate voltage.
Tightly bound trions in monolayer MoS2.
• K. Mak
• Physics
Nature materials
• 2013
The spectroscopic identification in a monolayer MoS(2) field-effect transistor of tightly bound negative trions, a quasiparticle composed of two electrons and a hole is reported, which has no analogue in conventional semiconductors.
Spin- and valley-dependent magneto-optical properties of MoS 2
• Physics
• 2013
We investigate the behavior of low-energy electrons in two-dimensional molybdenum disulfide when submitted to an external magnetic field. Highly degenerate Landau levels form in the material, between
Valley splitting and polarization by the Zeeman effect in monolayer MoSe2.
• Physics
Physical review letters
• 2014
This work has measured circularly polarized photoluminescence in monolayer MoSe2 under perpendicular magnetic fields up to 10 T and the magnitude of the Zeeman shift agrees with predicted magnetic moments for carriers in the conduction and valence bands.
Atomically thin MoS₂: a new direct-gap semiconductor.
• Physics, Materials Science
Physical review letters
• 2010
The electronic properties of ultrathin crystals of molybdenum disulfide consisting of N=1,2,…,6 S-Mo-S monolayers have been investigated by optical spectroscopy and the effect of quantum confinement on the material's electronic structure is traced.
Optical signature of symmetry variations and spin-valley coupling in atomically thin tungsten dichalcogenides
• Physics
Scientific reports
• 2013
The efficiency of second harmonic generation shows a dramatic even-odd oscillation with the number of layers, consistent with the presence (absence) of inversion symmetry in even-layer (odd-layer) and the giant spin-valley coupling which fully suppresses interlayer hopping at valence band edge near K points.
Valley-dependent spin polarization in bulk MoS2 with broken inversion symmetry.
• Physics
Nature nanotechnology
• 2014
The direct observation of valley-dependent out-of-plane spin polarization in an archetypal transition-metal dichalcogenide--MoS2--using spin- and angle-resolved photoemission spectroscopy is reported, in fair agreement with a first-principles theoretical prediction.
Exciton absorption spectra of MoS2 crystals in high magnetic fields up to 150 T
• Physics
• 2000
We have measured the absorption spectra of a cleaned MoS2 natural crystal in high magnetic fields up to 150 T in a Faraday configuration, and we have found Zeeman splitting and a diamagnetic shift of
Valley dynamics probed through charged and neutral exciton emission in monolayer WSe2
• Physics
• 2014
Optical interband transitions in monolayer transition metal dichalcogenides such as WSe2 and MoS2 are governed by chiral selection rules. This allows efficient optical initialization of an electron
Control of valley polarization in monolayer MoS2 by optical helicity.
• Physics
Nature nanotechnology
• 2012
It is demonstrated that optical pumping with circularly polarized light can achieve complete dynamic valley polarization in monolayer MoS(2) (refs 11, 12), a two-dimensional non-centrosymmetric crystal with direct energy gaps at two valleys.