"Negative" diamagnetism of three-dimensional arrays of semiconductor nano-rings

Abstract

We theoretically study the orbital diamagnetic response of three-dimensional arrays of embedded InAs/GaAs wobbled nano-rings. To simulate the rings' magnetic characteristics, we use the effective one band Hamiltonian (energy and position-dependent electron effective mass and Lande factor) and smooth three-dimensional confinement potential that is mapping the actual strain and material content inside the rings. First, we obtain the magnetic susceptibility of an individual nano-ring. Once it is achieved, using the Claussius-Mossotti relation we estimate the effective susceptibility of three-dimensional arrays of the rings. We show that conventionally diamagnetic InAs/GaAs ring structures under certain conditions can demonstrate the positive peak of the effective magnetic susceptibility of the arrays, that we call negative-diamagnetic response. The negative-diamagnetic (positive susceptibility) peak remains Lorentz-like shaped and gradually disappears when the rings' concentration in the arrays decreases. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim