Finite Temperature Phase Transitions in the multicomponent Hubbard model

大将 梁取, Hiromasa Yanatori, 昌久 古賀 +1 more

Hiromasa Yanatori, Akihisa Koga

We investigate the $\mathrm{SU}(N)$ Hubbard model for the multicomponent fermionic optical lattice system, combining dynamical mean-field theory with the continuous-time quantum Monte Carlo method. We obtain the finite-temperature phase diagrams with $N\ensuremath{\le}6$ and find that low-temperature properties depend on the parity of the components. The magnetically ordered state competes with the correlated metallic state in the system with an even number of components $(N\ensuremath{\ge}4)$, yielding the first-order phase transition. It is also clarified that in the odd-component system, the ordered state is realized at relatively lower temperatures and the critical temperature is constant in the strong coupling limit.

G. Migliorini, A. Nihat Berker

Igor K. Kudryavtsev, A N Meleshko, A. S. Shumovskiǐ

A study is made of a phase transition in a multicomponent system of two-level atoms interacting with a finite set of electromagnetic field modes. It is shown that the coupling between the components increases the temperature of a phase transition to a state characterized by ordering in the atomic subsystem and simultaneous filling of the photon modes.

I. V. Tokatly

The $ν$-component two-dimensional (2D) Bose liquid is considered. It is shown that the finite temperature phase transition exists in this 2D continuously degenerate multicomponent system. The new type of quasi-long-range order occurs as a result of this transition. The correlation function in ordered state is a product of the power-law XY-universality class type function and the exponential function corresponding to the $SU(ν)$ invariant model. The transition temperature is calculated for the diluted system. It is found that the physical mechanism of the phase transition is changed when $ν$ exceeds the critical value $ν_c = 4$. The experimental realization of the considered model is discussed briefly.

Matteo Rizzi, Rosario Fazio