Interaction effects on persistent current of ballistic cylindrical nanostructures

Abstract

We consider clean cylindrical nanostructures with an applied longitudinal static magnetic field. Without Coulomb interaction, the field induces, for particular values, points of degeneracy where a change of ground state takes place due to Aharonov-Bohm effect. The Coulomb potential introduces interaction between the electronic configurations. As a consequence, when there is degeneracy, the ground state of the system becomes a many body state -unable to be described by a mean-field theory -and a gap is opened. To study this problem, we propose a variational multireference wave function which goes beyond the Hartree-Fock approximation. Using this ansatz, in addition to the avoided crossing formation, two other effects of the electron-electron interaction are pointed out: (i) the long-range part of the Coulomb potential tends to shift the position in magnetic field of the (avoided) crossing points and, (ii) at the points of (near) degeneracy, the interaction can drive the system from a singlet to a triplet state inducing new real crossing points in the ground state energy curve as function of the field. Such crossings should appear in various experiments as sudden changes in the response of the system (magnetoconductance, magnetopolarisability,...) when the magnetic field is tuned.

Persistent currents and electronic properties of Mandelbrot quantum rings

“…The quantum rings geometries have many practical applications in nanoelectronics and spintronics devices, including spin switch 11 , including spin filters 12 , Tunable pure spin currents devices 13 , spin beam splitters 14 , solar cells 15 , light emitting diodes 16 , terahertz detectors 17 , 18 , etc. For this purpose different shapes considered so far are multi-shells quantum rings 19 , triangular quantum rings 20 , chiral toroidal carbon nanotubes 21 , few-site Hubbard rings with up to second-nearest neighbor coupling embedded to a ring-shaped lead 22 , ballistic cylindrical nanostructures 23 , rings perturbed with a quantum well 24 , etc.…”