Theory of diamagnetism in an asymmetrical vertical quantum dot molecule

Abstract

We consider a system of two vertical lens-shaped quantum dots. The quantum dots have substantially different diameters in contrast to most of the investigated structures. We demonstrate theoretically a possibility to relocate the ground-state electronic wave function from one dot to another by applying an external magnetic field along the structure's growth direction. The relocation correlates with the anticrossing behavior of the two lowest electronic energy states of the quantum dot molecule. This effect originates from a nonuniform diamagnetic shift for the electronic states located in different dots and generates unusual features of the magnetization and magnetic susceptibility of the system. At low temperature, the differential susceptibility of the system has a positive peak. With increasing temperature the peak gradually disappears. From our results it follows the opportunity to design nonmagnetic semiconductor nanostructures with unusual magnetic properties.