Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

The de Broglie Wavelength02:32

The de Broglie Wavelength

25.3K
In the macroscopic world, objects that are large enough to be seen by the naked eye follow the rules of classical physics. A billiard ball moving on a table will behave like a particle; it will continue traveling in a straight line unless it collides with another ball, or it is acted on by some other force, such as friction. The ball has a well-defined position and velocity or well-defined momentum, p = mv, which is defined by mass m and velocity v at any given moment. This is the typical...
25.3K
NMR Spectroscopy: Spin–Spin Coupling01:08

NMR Spectroscopy: Spin–Spin Coupling

1.3K
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved...
1.3K
Spin–Spin Coupling: One-Bond Coupling01:17

Spin–Spin Coupling: One-Bond Coupling

948
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,...
948
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)01:20

Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)

974
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
974
Atomic Nuclei: Nuclear Spin State Overview01:03

Atomic Nuclei: Nuclear Spin State Overview

884
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...
884
Quantum Numbers02:43

Quantum Numbers

34.3K
It is said that the energy of an electron in an atom is quantized; that is, it can be equal only to certain specific values and can jump from one energy level to another but not transition smoothly or stay between these levels.
34.3K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Probing Moiré Excitons in MoSe<sub>2</sub>/WSe<sub>2</sub> Heterobilayers by Combined Micro-photoluminescence and Lateral Force Microscopy.

Nano letters·2026
Same author

Thermoelectricity of Moiré Heavy Fermions in MoTe_{2}/WSe_{2} Bilayers.

Physical review letters·2026
Same author

Imaging the flat bands of magic-angle graphene reshaped by interactions.

Nature·2026
Same author

A compact low-power valveless piezoelectric micropump with a nested rectification structure.

Lab on a chip·2026
Same author

Voxel-based model predicts proton-induced brain necrosis using let and ventricular distance.

Medical dosimetry : official journal of the American Association of Medical Dosimetrists·2026
Same author

Electric-Field-Tuned Consecutive Topological Phase Transitions between Distinct Correlated Insulators in Moiré MoTe_{2}/WSe_{2} Heterobilayer.

Physical review letters·2026

Related Experiment Video

Updated: Jun 8, 2025

Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication
08:50

Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication

Published on: November 28, 2017

9.1K

Double Quantum Spin Hall Phase in Moiré WSe2.

Kaifei Kang1, Yichen Qiu2, Kenji Watanabe3

  • 1School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States.

Nano Letters
|November 7, 2024
PubMed
Summary

Researchers discovered a novel Quantum Spin Hall (QSH) phase in twisted bilayer WSe2, exhibiting multiple helical edge states. This breakthrough challenges previous limitations in material science for topological insulators.

Keywords:
Double quantum spin Hall insulatorHelical edge state transportMoiré semiconductorsTopological protection by Ising spin conservation

More Related Videos

Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform
05:39

Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform

Published on: August 2, 2019

9.5K
Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating
10:36

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating

Published on: April 12, 2018

11.4K

Related Experiment Videos

Last Updated: Jun 8, 2025

Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication
08:50

Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication

Published on: November 28, 2017

9.1K
Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform
05:39

Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform

Published on: August 2, 2019

9.5K
Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating
10:36

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating

Published on: April 12, 2018

11.4K

Area of Science:

  • Condensed matter physics
  • Materials science
  • Topological matter

Background:

  • Quantum Spin Hall (QSH) insulators feature topologically protected helical edge states.
  • Achieving multiple edge state pairs is challenging due to spin mixing.

Purpose of the Study:

  • To experimentally demonstrate a QSH phase with multiple helical edge state pairs.
  • Investigate the transport properties of these states in twisted bilayer WSe2.

Main Methods:

  • Fabrication and characterization of twisted bilayer WSe2.
  • Transport measurements at various Moiré hole filling factors (ν = 2 and 4).
  • Magnetic field dependence studies (in-plane and out-of-plane).

Main Results:

  • Observed nearly quantized resistance plateaus (within 10%) at ν = 2 and 4.
  • Demonstrated large nonlocal transport consistent with helical edge states.
  • Bulk remained insulating, with resistance showing unique magnetic field dependencies.

Conclusions:

  • Experimental evidence for a QSH phase with one and two pairs of helical edge states in twisted bilayer WSe2.
  • Results align with theoretical models of quantum transport in high spin Chern bands.
  • Ising spin conservation symmetry plays a key role in protecting these states.