Oscillatory persistent currents in quantum rings: semiconductors versus superconductorsOscillatory persistent currents in quantum rings: semiconductors versus superconductors
Faculty of Sciences. Physics
Theory of quantum systems and complex systems
Department of Physics
Physica: C: superconductivity. - Amsterdam
470(2010):19, p. 848-852
University of Antwerp
Persistent currents are a hallmark of superconductivity in metals. To observe those dissipationless currents in a non-superconducting ring, the circumference of the ring must be short enough so that the phase coherence of the electronic wave functions is preserved around the loop. Recent progress in the fabrication of self-assembled semiconductor quantum rings (SAQRs), which can be filled with only a few (12) electrons, has offered the unique possibility to study the magnetic-field-induced oscillations in the persistent current carried by a single electron. In this paper, we discuss similarities and distinctions between the behavior of persistent currents in semiconductor and superconductor samples and give an overview of the recent results for oscillatory persistent currents in SAQRs. Although the real SAQR shape differs strongly from an idealized circular-symmetric open ring structure, the AharonovBohm oscillations of the magnetization survive, as observed in low temperature magnetization measurements on InxGa1−xAs/GaAs SAQRs.