The repulsive Hubbard model has been immensely useful in understanding strongly
correlated electron systems and serves as the paradigmatic model of the field. Despite its …

One of Feynman's early applications of path integrals was to superfluid He 4. He showed
that the thermodynamic properties of Bose systems are exactly equivalent to those of a …

Magnetic properties of materials ranging from conventional ferromagnetic metals to strongly
correlated materials such as cuprates originate from Coulomb exchange interactions. The …

Abstract In the attractive Hubbard Model (and some extended versions of it), the ground
state is proved to have spin angular momentum S= 0 for every (even) electron filling. In the …

Quantum interference can deeply alter the nature of many-body phases of matter. In the
case of the Hubbard model, Nagaoka proved that introducing a single itinerant charge can …

We consider conduction electrons in a narrow s band with a strong repulsive potential which
acts when two electrons are at the same atomic site. It is assumed that the electron-transfer …

One of the main applications of future quantum computers will be the simulation of quantum
models. While the evolution of a quantum state under a Hamiltonian is straightforward (if …

We study a class of Hubbard models in which the corresponding single-electron ground
states have bulk degeneracy. We prove that the ground states of the models exhibit …

The Theory of Magnetism is an important subfield of the theory of solids, and has guided a
long history of research into the phenomenon of magnetism. This book provides the …

The author discusses some of the properties of the Hubbard model on a line graph with n
vertices. It is shown that the model has ferromagnetic ground states if the interaction is …