Transport properties of achiral carbon tori in external fields

Electronic and transport properties of achiral carbon tori in electric and magnetic fields are studied by the tight-binding model including the curvature effect. Electronic states are strongly affected by the direction and the magnitude of the electric field. Moreover, the magnetic field enhances the modulation of electronic states. The variation of state energies with external fields can be reflected further in transport properties such as conductance and thermopower. The modulation of external fields in transport properties is very different in a variety of achiral carbon tori. The differences include (I) the position, the height, and the width of conductance, and (II) the sign, the oscillatory behavior, and the dip-peak (or peak-dip) structure of thermopower. Additionally, transport properties of armchair carbon tori are more sensitive to the perpendicular magnetic fields than those of zigzag carbon tori.