5 research outputs found
Magnetic phases of one-dimensional lattices with 2 to 4 fermions per site
We study the spectral and magnetic properties of one-dimensional lattices
filled with 2 to 4 fermions (with spin 1/2) per lattice site. We use a
generalized Hubbard model that takes account all interactions on a lattice
site, and solve the many-particle problem by exact diagonalization. We find an
intriguing magnetic phase diagram which includes ferromagnetism, spin-one
Heisenberg antiferromagnetism, and orbital antiferromagnetism.Comment: 8 pages, 6 figure
Spectral properties of rotating electrons in quantum dots and their relation to quantum Hall liquids
The exact diagonalization technique is used to study many-particle properties
of interacting electrons with spin, confined in a two-dimensional harmonic
potential. The single-particle basis is limited to the lowest Landau level. The
results are analyzed as a function of the total angular momentum of the system.
Only at angular momenta corresponding to the filling factors 1, 1/3, 1/5 etc.
the system is fully polarized. The lowest energy states exhibit spin-waves,
domains, and localization, depending on the angular momentum. Vortices exist
only at excited polarized states. The high angular momentum limit shows
localization of electrons and separation of the charge and spin excitations.Comment: 14 pages 18 figure
Magnetism of quantum dot clusters: A Hubbard model study
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.Comment: 9 pages, 9 figure