62 citations · 149 across the 8 of their papers we have counts for
9 papers · 1 filter
Correlation and confinement induced itinerant ferromagnetism in chain structures
Reka Trencsenyi, Endre Kovacs, Zsolt Gulacsi
Using a positive semidefinite operator technique one deduces exact ground states for a zig-zag hexagon chain described by a non-integrable Hubbard model with on-site repulsion. Fla…
Delocalization effect of the Hubbard repulsion in exact terms and two dimensions
Zsolt Gulacsi
The genuine physical reasons explaining the delocalization effect of the Hubbard repulsion U are analyzed. First it is shown that always when this effect is observed, U acts on the…
Quadratic operators used in deducing exact ground states for correlated systems: ferromagnetism at half filling provided by a dispersive band
Istvan Chalupa, Zsolt Gulacsi
Quadratic operators are used in transforming the model Hamiltonian (H) of one correlated and dispersive band in an unique positive semidefinite form coopting both the kinetic and i…
Exact many-electron ground states on the diamond Hubbard chain
Zsolt Gulacsi, Arno Kampf, Dieter Vollhardt
Exact ground states of interacting electrons on the diamond Hubbard chain in a magnetic field are constructed which exhibit a wide range of properties such as flat-band ferromagnet…
Exact ground states for the four-electron problem in a two-dimensional finite Hubbard square system
Endre Kovacs, Zsolt Gulacsi
We present exact explicit analytical results describing the exact ground state of four electrons in a two dimensional square Hubbard cluster containing 16 sites taken with periodic…
Exact ground states for the four-electron problem in a Hubbard ladder
Endre Kovacs, Zsolt Gulacsi
The exact ground state of four electrons in an arbitrary large two leg Hubbard ladder is deduced from nine analytic and explicit linear equations. The used procedure is described,…