Related Experiment Video
Updated: Jun 29, 2026
11:42
Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
Weak localization of Dirac fermions in graphene
1Texas Center for Superconductivity, University of Houston, Houston, TX 77204, USA.
Physical Review Letters
|October 15, 2008
Summary
Weak localization in graphene Dirac fermions is observed in large samples but diminishes in smaller ones. This quantum interference effect is sensitive to sample size, temperature, and carrier concentration.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Mechanics
Background:
- Charged impurities significantly influence electron behavior in materials.
- Quantum interference effects, like weak localization, are crucial for understanding conductivity in 2D materials.
- Dirac fermions in graphene exhibit unique electronic properties.
Purpose of the Study:
- To investigate the weak localization effect in graphene Dirac fermions.
- To analyze the impact of charged impurities on quantum interference corrections to conductivity.
- To determine the dependence of weak localization on carrier concentration, temperature, magnetic field, and sample size.
Main Methods:
- Evaluating quantum interference correction to conductivity.
- Utilizing inelastic scattering rates from electron-electron interactions.
- Analyzing experimental data for various sample sizes and conditions.
Main Results:
- Weak localization is observed in large graphene samples with finite carrier doping.
- The strength of weak localization decreases or is quenched in samples smaller than a few microns at low temperatures.
- The system may exhibit delocalization near zero doping.
- Minimum conductivity at low temperatures aligns with experimental observations for typical sample sizes.
Conclusions:
- Sample size is a critical factor in observing weak localization in graphene.
- Electron-electron interactions and charged impurities play key roles in modulating quantum interference effects.
- The findings provide insights into the electronic transport properties of graphene relevant for device applications.
Related Concept Videos
02:42Valence Bond Theory
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...
01:18Fermi Level
The Fermi-Dirac function is represented by an S-shaped curve indicating the probability of an energy state being occupied by an electron at a given temperature. The Fermi level is the energy level at which there is a fifty percent chance of finding an electron, and it is positioned between the lower-energy valence band and the higher-energy conduction band.
At absolute zero temperature, electrons fill all energy states up to the Fermi level, leaving upper states empty. As the temperature rises,...
At absolute zero temperature, electrons fill all energy states up to the Fermi level, leaving upper states empty. As the temperature rises,...
01:27π Electron Effects on Chemical Shift: Overview
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, resulting in...
01:12Fermi Level Dynamics
The vacuum level denotes the energy threshold required for an electron to escape from a material surface. It is usually positioned above the conduction band of a semiconductor and acts as a benchmark for comparing electron energies within various materials.
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
01:04IR Absorption Frequency: Delocalization
Electron delocalization refers to the distribution of electrons across multiple atoms within a molecule rather than being confined to a single atom or bond. This phenomenon is common in systems with conjugated bonds—structures where alternating single and double bonds allow π-electrons to move freely across the network. The movement of electrons stabilizes the molecule and can affect various chemical properties, including vibrational frequencies observed in IR spectroscopy.
In IR spectroscopy,...
In IR spectroscopy,...
01:26Imperfections in Crystal Structure: Stoichiometric Point Defects
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...