Related Experiment Video
Updated: Mar 28, 2026
10:36
Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating
Published on: April 12, 2018
12.1K
Anomalous temperature-dependent spin-valley polarization in monolayer WS2
A T Hanbicki1, G Kioseoglou2,3, M Currie4
1Materials Science and Technology Division, Naval Research Laboratory, Washington, DC 20375.
Scientific Reports
|January 6, 2016
Summary
Single-layer transition metal dichalcogenides (TMDs) show potential for valleytronics. Charged excitons (trions) in WS2 exhibit significant polarization and unique temperature dependence, enabling control via gate voltage.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Single layers of transition metal dichalcogenides (TMDs) are direct gap semiconductors with unique valley properties.
- Utilizing the valley index as a state variable is promising but faces challenges like intervalley scattering and multiparticle interactions.
Purpose of the Study:
- To investigate the photoluminescence polarization of single-layer WS2, specifically from neutral excitons and charged excitons (trions).
- To explore the temperature dependence of trion emission and its implications for understanding dominant physical mechanisms.
Main Methods:
- Preparation of single-layer WS2 films.
- Excitation with circularly polarized light.
- Measurement of photoluminescence polarization and its temperature dependence.
Main Results:
- Neutral exciton emission showed zero polarization.
- Trion emission exhibited significant polarization (28%) at room temperature.
- Trion emission displayed a unique, non-monotonic temperature dependence.
Conclusions:
- The observed temperature dependence confirms the multiparticle nature of trions and reveals dominant mechanisms including intervalley scattering, electron-hole recombination, and Auger processes.
- Gate voltage can be used to modulate the polarization and intensity of emitted light from TMD structures, highlighting potential for valleytronics applications.
More Related Videos
Related Concept Videos
02:42Valence Bond Theory
11.6K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
11.6K
01:03Atomic Nuclei: Nuclear Spin State Overview
2.2K
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...
2.2K
03:06The Pauli Exclusion Principle
61.3K
The arrangement of electrons in the orbitals of an atom is called its electron configuration. We describe an electron configuration with a symbol that contains three pieces of information:
61.3K
01:22Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
1.7K
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive.
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
1.7K
01:27π Electron Effects on Chemical Shift: Overview
1.9K
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0,...
1.9K
01:17Spin–Spin Coupling: One-Bond Coupling
1.6K
Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...
1.6K