Magnetic-flux-induced persistent currents in nonlinear mesoscopic rings

National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
Journal of Applied Physics (Impact Factor: 2.18). 05/2011; 109(7):07E139 - 07E139-3. DOI: 10.1063/1.3562257
Source: IEEE Xplore


We investigate magnetic-flux-induced persistent currents (PCs) in a one-dimensional nonlinear mesoscopic ring based on the Frenkel–Kontorova (FK) model. By applying a transfer-matrix technique, the energy spectra, the PCs, and the Thouless exponent are theoretically obtained. It is shown that the energy spectrum splits into sub-bands when the on-site energy is gradually increased, and in the flux-dependent energy spectra, the energy levels show different behaviors over the transition by breaking of analyticity. Meanwhile, the PC is determined by the magnetic flux, the on-site energy, and the Fermi level. The increment of the on-site energy leads to a dramatic suppression of the PC. When the Fermi level is in the vicinity of “band” gaps, the PC is limited considerably; otherwise, the PC increases by several orders of magnitude. The suppressed PC is related to the electronic localization of the FK ring, which is described by the Thouless exponents. Our investigations provide detailed information about the influence of nonlinear structure on the PC and contribute to its potential application in quantum devices.

2 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigate magnetic-flux-induced persistent currents in one-dimensional symmetric-polymer (SP) mesoscopic ring, where a defect cluster is embedded into two periodic clusters and the whole cluster possesses mirror symmetry. Under tight-binding approximation, the flux-dependent energy spectra, electronic wave functions, and persistent currents are obtained. It is shown that the energy spectra form band structure and the defect modes appear in the band gap. The persistent current (PC) depends on the magnetic flux, the site energy, and the Fermi level. Particularly, by changing the Fermi level, the SP ring presents metallic and insulative features alternately. Our investigations provide a possible model to explain the anomalously large PC observed in some experiments and contribute to the potential application in quantum-switch devices.
    Journal of Applied Physics 04/2006; 99(8):08F710-08F710-3. DOI:10.1063/1.2172562 · 2.18 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We study the effect of electron-electron interaction on transport through a tunnel-coupled single-channel ring. We find that the conductance as a function of magnetic flux shows a series of interaction-induced resonances that survive thermal averaging. The period of the series is given by the interaction strength α. The physics behind this behavior is the blocking of the tunneling current by the circular current. The main mechanism of dephasing is due to circular-current fluctuations. The dephasing rate is proportional to the tunneling rate and does not depend on α.
    Physical Review Letters 07/2010; 105(3):036402. DOI:10.1103/PhysRevLett.105.036402 · 7.51 Impact Factor
Show more