Electronic and magnetic properties of carbon tori and carbon nanotubes under external fields
| Autor: | Chia-Chang Tsai, 蔡佳璋 |
|---|---|
| Rok vydání: | 2005 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 93 Zero-dimensional carbon tori and one-dimensional carbon nanotubes are studied for their electronic and magnetic properties. The effects due to the direction and the magnitude of the magnetic field, the transverse electric field, the height, the radius, the chiral angle, and the temperature are investigated in detail. The nearest-neighbor tight-binding model with the curvature effects are used to calculate electronic structures. The magnetic field might destroy state degeneracy, lead to semiconductor-metal transitions, modulate energy spacings, cause Aharonov-Bohm (AB) oscillations, alter edge states, and change subband curvatures or effective masses. The transverse electric field in carbon tori could induce similar effects except the AB oscillations. Due to the quantum size effect, there are certain important differences between carbon tori and carbon nanotubes in electronic properties, such as density of states, state degeneracy, and energy gap. The main features of electronic properties are directly reflected in magnetic properties. Magnetism and strength of magnetic response are mainly determined by the geometric structures and the magnitude and the direction of magnetic field. Carbon tori quite differ from carbon nanotubes in magnetic properties, e.g., the paramagnetic or diamagnetic behavior at small magnetic field, the magnetic susceptibility, and the critical magnetic field in changing magnetism. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|