Hannover 2010 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

Q: Fachverband Quantenoptik und Photonik

Q 51: Quantum Gases: Fermions

Q 51.7: Vortrag

Donnerstag, 11. März 2010, 15:30–15:45, E 001

Mott insulator phases of spin-3/2 fermions in one-dimensional lattices. — •Karen Rodríguez, Arturo Argüelles, Maria Colomé-Tatché, Temo Vekua, and Luis Santos — Institut für Theoretische Physik, Leibniz Univesität Hannover, Hannover,Deutschland

We study the ground state phase diagram of repulsive spin-3/2 fermions at zero magnetization in the presence of quadratic Zeeman effect(QZE). Starting from the Hamiltonian of the four-component Hubbard model we derive the effective hard-core Hamiltonian, that can be understood as a spin-chain model. This model presents effective coupling constants which show a non-trivial dependence induced by the interplay between quadratic Zeeman effect and spin-changing collision. In the absence of a quadratic Zeeman effect the ground state of the system is either in the dimer (spin Peierls) phase or in the spin liquid one. Applying a non-zero quadratic Zeeman effect the system breaks the degeneracy between the 1/2 and the 3/2 spin components, resulting in a phase transition into an effective pseudo-spin 1/2 isotropic Heisenberg antiferromagnet for a sufficiently large QZE. We characterize by means of DMRG calculations the ground state properties, including spin-spin and dimer-dimer correlations, magnetization gap and chirality, for the different regimes and determine the boundaries between the different phases. We characterize the transition between dimer phase and effective Heisenberg antiferromagnet by means of exact diagonalization techniques.