Magneto-optical properties of carbon toroids: Influence of geometry and magnetic field

Magneto-optical excitations of carbon toroids by the cross polarized light are studied within the gradient approximation. Their dependences on the magnitude (φ) and the direction (α) of the magnetic field vary with the changes in the toroid geometry (chiral angle, height, and radius). The absorption spectra of armchair toroids are hardly affected by φ and α. In contrast, the absorption peaks of zigzag toroids, due to the changes in the energy spacing and the destruction of the state degeneracy, obviously split and shift as φ and α vary. For different α's, the threshold excitation energy (ωₜₕ) displays the periodic Aharonov-Bohm oscillations or monotonously decreases as φ increases. Moreover, the φ dependences of ωₜₕ on the toroid height and the toroid radius are significantly different.