Related Experiment Video
Updated: Dec 28, 2025
10:36
Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials
Published on: January 21, 2016
11.0K
Helical quantum Hall phase in graphene on SrTiO3
Louis Veyrat1, Corentin Déprez1, Alexis Coissard1
1Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France.
Science (New York, N.Y.)
|February 15, 2020
Summary
Researchers achieved a topological phase in graphene using a strontium titanate substrate, enabling robust helical edge transport. This breakthrough opens doors for spintronics and topological quantum computation.
Area of Science:
- Condensed Matter Physics
- Materials Science
Background:
- Graphene's ground state under magnetic fields was theoretically predicted to be a quantum Hall topological insulator.
- Experimental observations often show an insulating state due to lattice interactions, differing from theoretical predictions.
Purpose of the Study:
- To experimentally realize the predicted topological phase in graphene.
- To investigate the role of Coulomb interaction screening in achieving this phase.
Main Methods:
- Utilizing a strontium titanate (SrTiO3) substrate with a high dielectric constant to screen Coulomb interactions in graphene.
- Applying perpendicular magnetic fields to tune the graphene zeroth Landau level.
Main Results:
- Achieved a topological phase in graphene's ground state.
- Observed robust helical edge transport at low magnetic fields (1 tesla) and elevated temperatures (up to 110 K) over micron-long distances.
Conclusions:
- Demonstrated a method to access graphene's topological quantum Hall insulator state.
- The developed graphene platform shows promise for spintronics and topological quantum computation applications.
Related Concept Videos
03:24Hybridization of Atomic Orbitals I
64.7K
The mathematical expression known as the wave function, ψ, contains information about each orbital and the wavelike properties of electrons in an isolated atom. When atoms are bound together in a molecule, the wave functions combine to produce new mathematical descriptions that have different shapes. This process of combining the wave functions for atomic orbitals is called hybridization and is mathematically accomplished by the linear combination of atomic orbitals. The new orbitals that...
64.7K
03:35Hybridization of Atomic Orbitals II
47.1K
sp3d and sp3d 2 Hybridization
47.1K
02:30Chirality at Nitrogen, Phosphorus, and Sulfur
6.7K
Chirality is most prevalent in carbon-based tetrahedral compounds, but this important facet of molecular symmetry extends to sp3-hybridized nitrogen, phosphorus and sulfur centers, including trivalent molecules with lone pairs. Here, the lone pair behaves as a functional group in addition to the other three substituents to form an analogous tetrahedral center that can be chiral.
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...
6.7K
01:30The Hall Effect
3.8K
Edwin H. Hall, in the year 1879, devised an experiment that could be used to identify the polarity of the predominant charge carriers in a conducting material. From a historical perspective, this experiment was the first to demonstrate that the charge carriers in most metals are negative.
3.8K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
47.6K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
47.6K
01:27π Electron Effects on Chemical Shift: Overview
1.5K
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,...
1.5K