Magneto-Transport in Closed and Open Mesoscopic Loop Structures: A Review

Magneto-transport properties in closed and open loop structures are carefully reviewed within a tight-binding formalism. A novel mesoscopic phenomenon where a non-vanishing current is observed in a conducting loop upon the application of an Aharonov-Bohm flux phi and we explore its behavior in the aspects of quantum phase coherence, electron-electron correlation and disorder. The essential results are analyzed in three different parts. First, we examine the behavior of persistent current in different branches of a zigzag carbon nanotube within a Hartree-Fock mean field approach using the second quantized formulation. The phase reversal of persistent current in several branches as a function of Hubbard interaction is found to exhibit interesting patterns. Our numerical results suggest a filling-dependent metal-insulator transition in a zigzag carbon nanotube. Next, we address the behavior of persistent current in an ordered-disordered separated nanotube keeping in mind a possible experimental realization of shell-doped nanowire which can provide a strange electronic behavior rather than uniformly doped nanowires. Finally, we focus our attention on the behavior of persistent current in an open loop geometry where we clamp an ordered binary alloy ring between two ideal semi-infinite electrodes to make an electrode-ring-electrode bridge. From our investigation we propose that under suitable choices of the parameter values the system can act as a p-type or an n-type semiconductor.