Enhancement Of Persistent Current Research Articles

Enhancement of persistent currents and magnetic fields in a two dimensional quantum ring

We present the study of the SiGe quantum ring (QR) modeled by an anharmonic axially symmetric potential with a centrifugal core in the effective mass approximation. We show how the femtosecond laser pulses (FLPs) can be used efficiently for controlling the induced current and magnetic field. We have compared the strength of induced currents and magnetic fields with and without pulsed laser which shows a substantial change. The spin-orbit interaction (SOI) and Zeeman energy show a massive impact on the generation and enhancement of these induced current and magnetic fields. These induced currents and magnetic fields have many applications in interdisciplinary areas. We have shown that the SOI presence with the FLP fields while competing with the confinement strength lowers the strength of the induced current and field.

N-electron train effect on the enhancement of persistent current

We describe a train effect which may exist in small metallic and semiconductor rings. It is associated with the cooperative motion of a “train” of N electrons on the ring. It may be related to the long-standing problem of the persistent current enhancement. The train arises via an excitation or a back flow of spin waves or of interchannel charge density sound modes in a multichannel ring. Disorder has little influence on the “train” current. We calculated the persisent current for the Hubbard model by the Bethe ansatz. The fractional M N periodicities of the persistent current serve as an indication of the electron “train”, where M is the number of spin-up electrons or electrons in a single channel.

Enhancement of Persistent Currents by Hubbard Interactions in Disordered 1D Rings: Avoided Level Crossings Interpretation

We study effects of local electron interactions on the persistent current of one dimensional disordered rings. For different realizations of disorder we compute the current as a function of Aharonov-Bohm flux to zeroth and first orders in the Hubbard interaction. We find that the persistent current is {\em enhanced} by onsite interactions. Using an avoided level crossings approach, we derive analytic formulas which explain the numerical results at weak disorder. The same approach also explains the opposite effect (suppression) found for spinless fermion models with intersite interactions.