Magnetism of quantum dot clusters: a Hubbard model study
NanoScience Center, Department of Physics, 40014 University of Jyväskylä, Jyväskylä, Finland
2 Inspecta LTD, 02151 Espoo, Finland
Corresponding author: a Matti.Manninen@phys.jyu.fi
Published online: 16 July 2008
Magnetic properties of two and three-dimensional clusters of quantum dots are studied with exact diagonalization of a generalized Hubbard model. We study the weak coupling limit, where the electrons interact only within a quantum dot and consider cases where the second or third harmonic oscillator shell is partially filled. The results show that in the case of half-filled shell the magnetism is determined by the antiferromagnetic Heisenberg model with spin 1/2, 1 or 3/2, depending on the number of electrons in the open shell. For other fillings the system in most cases favors a large total spin, indicating a ferromagnetic coupling between the dots.
PACS: 73.21.La – Quantum dots / 75.75.+a – Magnetic properties of nanostructures / 71.10.-w – Theories and models of many-electron systems
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008