arXiv subjects

Yue-Xun Li

Publications and source records attributed to Yue-Xun Li.

4 recordsLinked to original sources

arXiv2023

The energy limit in molecular alignment by femtosecond laser pulse

In this paper, we studied the optimal alignment and anti-alignment of O2 molecules by femtosecond laser pulse under different input energy. The results show that there is an energy limit in molecular alignment. The optimal molecular alignment and anti-alignment degree will never increase with the increase of laser energy when the input laser energy exceeds the energy limit. Besides, under the energy limit, the molecular optimal alignment (or anti-alignment) degree by using a shorter pulse duration (under 100 fs) will be about same when the input laser energy remained constant (different pulse duration and the peak power are chosen). Especially at a lower temperature of molecular assemble.

physics.optics↗

arXiv2021

Phase transitions of the dimerized Kane-Mele model with/without the strong interaction

The dimerized Kane-Mele model with/without the strong interaction is studied using analytical methods. The boundary of the topological phase transition of the model without strong interaction is obtained. Our results show that the occurrence of the transition only depends on dimerized parameter . From the one-particle spectrum, we obtain the completed phase diagram including the quantum spin Hall (QSH) state and the topologically trivial insulator. Then, using different mean-field methods, we investigate the Mott transition and the magnetic transition of the strongly correlated dimerized Kane-Mele model. In the region between the two transitions, the topological Mott insulator (TMI) with characters of Mott insulators and topological phases may be the most interesting phase. In this work, effects of the hopping anisotropy and Hubbard interaction U on boundaries of the two transitions are observed in detail. The completed phase diagram of the dimerized Kane-Mele-Hubbard model is also obtained in this work. Quantum fluctuations have extremely important influences on a quantum system. However, investigations are under the framework of the mean field treatment in this work and the effects of fluctuations in this model will be discussed in the future.

cond-mat.str-el↗

arXiv2021

The competition between the intrinsic and Rashba spin-orbit coupling and effects of correlations on Rashba SOC-driven transitions in the Kane-Mele model

We investigate, firstly, the effects of the Rashba SOC on the band structrue of the Kane-Mele model. The competition between the Rashba SOC and the intrinsic SOC can lead to the rich phenomenology. The Rashba SOC can drive the indirect and direct energy gap to close successively, but maintain the band touching between the valence band and the conduction band when the Rashba SOC is large enough to dominant the competition. We find that these touching points are located at $K$ and $K^{\prime}$ or/and some $2π/3$ rotationally symmetric points around $K$ and $K^{\prime}$ in the Brillouin zone. The indirect and direct energy gap closings correspond to the topologically trivial and non-trivial phase transitions respectively. For the small intrinsic SOC, the topologically non-trivial transition occurs when the ratio of the Rashba SOC to the intrinsic SOC is equal to the classical result, i.e. $2\sqrt{3}$. For the large intrinsic SOC, however, we find that the ratio decreases with the increasing intrinsic SOC. Secondly, using the slave-rotor mean field method we investigate the influences of the correlation on the Rashba SOC-driven topologically trivial and non-trivial transition in both the charge condensate and Mott regions. The topological Mott insulator with gapped or gapless spin excitations can arise from the interplay of the Rashba SOC and correlations.

cond-mat.str-el↗

arXiv2017

Multitude of phases in correlated lattice fermion systems with spin-dependent disorder

The magnetic phases induced by the interplay between disorder acting only on particles with a given spin projection ("spin-dependent disorder") and a local repulsive interaction is explored. To this end the magnetic ground state phase diagram of the Hubbard model at half-filling is computed within dynamical mean-field theory combined with the geometric average over disorder, which is able to describe Anderson localization. Five distinct phases are identified: a ferromagnetically polarized metal, two types of insulators, and two types of spin-selective localized phases. The latter four phases possess different long-range order of the spins. The predicted phase diagram may be tested experimentally using cold fermions in optical lattices subject to spin-dependent random potentials.

cond-mat.str-el↗