Physica E 26 (2005) 308–311 Biexcitons in artificial molecules with in-plane magnetic field Devis Bellucci à , Filippo Troiani, Guido Goldoni, Elisa Molinari INFM - National Research Center on nanoStructures and bioSystems at Surfaces (S3), Dipartimento di Fisica, Universita` degli Studi di Modena e Reggio Emilia, Via Campi 213/A, 41100 Modena, Italy Available online 23 November 2004 Abstract We theoretically investigate the effect of a magnetic field perpendicular to the tunneling direction on the ground-state properties of biexcitons in coupled quantum dots. The single-particle states are computed by numerically solving the 3D Scro¨dinger equation. The biexciton states are obtained by means of a configuration-interaction approach, which fully accounts for the intra- and inter-dot Coulomb correlations. We show that the biexciton ground state undergoes non- trivial transitions as a function of the applied magnetic field, which can be traced back to unexpected carrier localizations. r 2004 Elsevier B.V. All rights reserved. PACS: 73.21.La; 73.23.Hk Keywords: Coupled quantum dots; Coulomb correlations; Magnetic fields 1. Introduction Semiconductor quantum dots (QDs) are solid- state nanostructures which allow the confinement of carriers in all directions within dimensions smaller than their de Broglie wavelength. The energy spectrum consequently being discretized, QDs are often referred to as artificial atoms [1]. In recent years, the growth of QDs with tunable interdot barriers has been demonstrated [2]: the carrier tunneling determines a coherent coupling between neighbouring dots and a delocalization of the single-particle (SP) wavefunctions over the so- called artificial molecule (AM) [3]. Unlike single QDs, which are quasi-2D systems, AMs are characterized by a fully three-dimensional char- acter, and therefore show an enriched phenomen- ology. Besides, any QD-based quantum- information processing scheme requires a precise control of the interdot tunneling [4]. A convenient way to achieve such control is to apply a magnetic field perpendicular to the tunneling direction: in fact, the field tunes the bonding (B)-antibonding (AB) splitting D BAB ; thus inducing transitions between different coupling regimes, reminiscent ARTICLE IN PRESS www.elsevier.com/locate/physe 1386-9477/$-see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.physe.2004.08.095 à Corresponding author. E-mail address: dbellucci@unimore.it (D. Bellucci).