Related Experiment Video
Updated: May 25, 2026
09:00
Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
Published on: June 28, 2018
A bipolar spin-filtering effect in graphene zigzag nanoribbons with spin-orbit coupling
Jun-Feng Liu1, K S Chan, Jun Wang
1Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong, People's Republic of China. junfeliu@cityu.edu.hk
Nanotechnology
|February 11, 2012
Summary
We predict a large spin-filtering effect in graphene nanoribbons due to Rashba spin-orbit coupling. This effect enables the generation of bipolar spin-polarized currents by tuning the Fermi energy.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spintronics
Background:
- Graphene nanoribbons exhibit unique electronic properties.
- Spin-orbit coupling is crucial for spintronic applications.
- Controlling spin polarization in materials is a key challenge.
Purpose of the Study:
- To predict and explain a significant spin-filtering effect in graphene zigzag nanoribbons.
- To investigate the role of Rashba spin-orbit coupling in this phenomenon.
- To explore methods for generating bipolar spin-polarized currents.
Main Methods:
- Theoretical prediction of spin-filtering.
- Analysis of electron transport through graphene nanoribbons.
- Modeling the impact of potential barriers and width constrictions.
- Investigating electron-hole symmetry and time-reversal symmetry.
Main Results:
- A large spin-filtering effect is predicted in graphene zigzag nanoribbons.
- Maximum spin polarization is achieved under specific subband conditions.
- Potential barriers or width constrictions can induce this effect.
- Bipolar spin-polarized currents can be generated by tuning the Fermi energy.
Conclusions:
- Graphene nanoribbons with Rashba spin-orbit coupling are promising for spintronics.
- The predicted spin-filtering effect offers a pathway to control spin currents.
- Understanding electron-hole symmetry is key to generating bipolar spin currents.
Related Concept Videos
01:17Spin–Spin Coupling: One-Bond Coupling
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,...
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
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...
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...
01:22Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
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...
01:08Spin–Spin Coupling Constant: Overview
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
01:08NMR Spectroscopy: Spin–Spin Coupling
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 in...
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...