Tuning of electron g factors by electric fields in asymmetric InAs quantum dot molecules

Abstract

Most self-assembled quantum dot molecules (QDMs) are composed of dots of different sizes stemming from imperfect control of crystal growth. In this paper we use the intrinsic structural asymmetry to tune spin-polarized states by reversing electric fields. We calculate electron g factors of InAs/GaAs QDMs with inequivalent dots under external electric fields. The g factor in the asymmetric system exhibits remarkable tunability under the forward applied field. In contrast, it is not very sensitive to the backward electric field within the resonant region. Hence, different spin-polarized states can be switched by reversing an applied field. Furthermore, g factors for both bonding and anti-bonding states can be tuned to zero under the same positive field (6.6 mV nm−1) in the asymmetric QDM.