arXiv subjects

Irakli Titvinidze

Publications and source records attributed to Irakli Titvinidze.

22 records · Page 2Linked to original sources

arXiv2011

Effect of interactions on harmonically confined Bose-Fermi mixtures in optical lattices

We investigate a Bose-Fermi mixture in a three-dimensional optical lattice, trapped in a harmonic potential. Using Generalized Dynamical Mean-Field theory, which treats the Bose-Bose and Bose-Fermi interaction in a fully non-perturbative way, we show that for experimentally relevant parameters a peak in the condensate fraction close to the point of vanishing Bose-Fermi interaction is reproduced within a single band framework. We identify two physical mechanisms contributing to this effect: the spatial redistribution of particles when the interspecies interaction is changed and the reduced phase space for strong interactions, which results in a higher temperature at fixed entropy.

cond-mat.quant-gas↗

arXiv2011

Magnetism and domain formation in SU(3)-symmetric multi-species Fermi mixtures

We study the phase diagram of an SU(3)-symmetric mixture of three-component ultracold fermions with attractive interactions in an optical lattice, including the additional effect on the mixture of an effective three-body constraint induced by three-body losses. We address the properties of the system in $D \geq 2$ by using dynamical mean-field theory and variational Monte Carlo techniques. The phase diagram of the model shows a strong interplay between magnetism and superfluidity. In the absence of the three-body constraint (no losses), the system undergoes a phase transition from a color superfluid phase to a trionic phase, which shows additional particle density modulations at half-filling. Away from the particle-hole symmetric point the color superfluid phase is always spontaneously magnetized, leading to the formation of different color superfluid domains in systems where the total number of particles of each species is conserved. This can be seen as the SU(3) symmetric realization of a more general tendency to phase-separation in three-component Fermi mixtures. The three-body constraint strongly disfavors the trionic phase, stabilizing a (fully magnetized) color superfluid also at strong coupling. With increasing temperature we observe a transition to a non-magnetized SU(3) Fermi liquid phase.

cond-mat.quant-gas↗

arXiv2011

Canted Antiferromagnetic Order of Imbalanced Fermi-Fermi mixtures in Optical Lattices by Dynamical Mean-Field Theory

We investigate antiferromagnetic order of repulsively interacting fermionic atoms in an optical lattice by means of Dynamical Mean-Field Theory (DMFT). Special attention is paid to the case of an imbalanced mixture. We take into account the presence of an underlying harmonic trap, both in a local density approximation and by performing full Real-Space DMFT calculations. We consider the case that the particle density in the trap center is at half filling, leading to an antiferromagnetic region in the center, surrounded by a Fermi liquid region at the edge. In the case of an imbalanced mixture, the antiferromagnetism is directed perpendicular to the ferromagnetic polarization and canted. We pay special attention to the boundary structure between the antiferromagnetic and the Fermi liquid phase. For the moderately strong interactions considered here, no Stoner instability toward a ferromagnetic phase is found. Phase separation is only observed for strong imbalance and sufficiently large repulsion.

cond-mat.quant-gas↗

arXiv2003

Phase Diagram of the spin S=1/2 Extended XY model

The quantum phase transition in the ground state of the Extended spin S=1/2 XY model is studied in detail. Using the exact solution of the model the low temperature thermodynamics, as well as the ground state phase diagram of the model in the presence of applied uniform and/or staggered magnetic field are discussed.

cond-mat.str-el↗