ICFO-Institut de Ciències Fotòniques, Parc Mediterrani de la Tecnologia, E-08860 Castelldefels, Spain.
Phys Rev Lett. 2013 Mar 1;110(9):096405. doi: 10.1103/PhysRevLett.110.096405. Epub 2013 Feb 28.
As a minimal fermionic model with kinetic frustration, we study a system of spinless fermions in the lowest band of a triangular lattice with nearest-neighbor repulsion. We find that the combination of interactions and kinetic frustration leads to spontaneous symmetry breaking in various ways. Time-reversal symmetry can be broken by two types of loop current patterns, a chiral one and one that breaks the translational lattice symmetry. Moreover, the translational symmetry can also be broken by a density wave forming a kagome pattern or by a Peierls-type trimerization characterized by enhanced correlations among the sites of certain triangular plaquettes (giving a plaquette-centered density wave). We map out the phase diagram as it results from leading-order Ginzburg-Landau mean-field theory. Several experimental realizations of the type of system under study are possible with ultracold atoms in optical lattices.
作为一个具有动力学挫折的最小费米子模型，我们研究了一个在三角晶格最低能带中具有最近邻排斥的无自旋费米子系统。我们发现，相互作用和动力学挫折的组合以各种方式导致自发对称性破缺。时间反演对称性可以通过两种类型的环电流模式被打破，一种是手征的，另一种是打破晶格平移对称性的。此外，平移对称性也可以通过形成 kagome 图案的密度波或通过由特定三角形 plaquette （形成以 plaquette 为中心的密度波）的站点之间的相关性增强而被打破。我们通过主导阶的吉布斯-朗道平均场理论来描绘相图。在光学晶格中，研究类型的系统的几种实验实现是可能的。
