论文标题
fermion-fermion相互作用驱动的不稳定性和二次带交叉系统的关键性，而时间交流对称性破裂
Fermion-fermion interaction driven instability and criticality of quadratic band crossing systems with the breaking of time-reversal symmetry
论文作者
论文摘要
我们仔细研究了Fermion-Fermion的相互作用如何影响Kagomé晶格上具有二维带的二维旋转$ 1/2 $ fermionic System的低能状态。借助重新归一化的组方法，我们可以在相同的基础上处理各种效率相互作用，然后通过收集一环校正来建立费米子相互作用参数的耦合能量依赖性流，从中在低增强仪制度中从中提取许多有趣的结果。起初，各种羊毛屈服的相互作用激烈地相互竞争，并且不可避免地被参数空间中的某些固定点吸引，这些固定点群集成了三个定性截然不同的区域，这些区域在很大程度上依赖于材料的结构参数。此外，我们注意到伴随着一些对称破裂的不稳定性围绕不同种类的固定点触发。计算和比较十二个潜在候选者的敏感性表明，电荷密度波总是在所有其他不稳定性中占主导地位。顺便说一句，有几个转向的冠军，包括$ x $ - 电流，债券密度和手性和S波超导体。最后，我们意识到，在主要不稳定性附近的强烈波动更喜欢抑制状态的密度和特定的热量，以及在最低能量极限下准粒子的可压缩性。
We carefully study how the fermion-fermion interactions affect the low-energy states of a two-dimensional spin-$1/2$ fermionic system on the kagomé lattice with a quadratic band crossing point. With the help of the renormalization group approach, we can treat all kinds of fermionic interactions on the the same footing and then establish the coupled energy-dependent flows of fermionic interaction parameters via collecting one-loop corrections, from which a number of interesting results are extracted in the low-energy regime. At first, various sorts of fermion-fermion interactions furiously compete with each other and are inevitably attracted by certain fixed point in the parameter space, which clusters into three qualitatively distinct regions relying heavily upon the structure parameters of materials. In addition, we notice that an instability accompanied by some symmetry breaking is triggered around different sorts of fixed points. Computing and comparing susceptibilities of twelve potential candidates indicates that charge density wave always dominates over all other instabilities. Incidently, there exist several subleading ones including the $x$-current, bond density, and chiral plus s-wave superconductors. Finally, we realize that strong fluctuations nearby the leading instability prefer to suppress density of states and specific heat as well compressibility of quasiparticles in the lowest-energy limit.
