稀土金属碳化物Re2C3中非常规六重、四重和三重激发的观测
Observation of unconventional six-fold, four-fold and three-fold excitations in rare-earth-metal carbide Re2C3
摘要：
近年来，三重、四重、六重和八重费米子等非常规费米子引起了人们的密切关注。然而，承载非常规费米子的具体材料仍然非常稀缺。本文通过第一性原理计算和对称性分析，揭示了Re_2C_3（Re = Y，La，Ce，Pr，Nd，Sm，Tb，Dy，Ho，Er，Tm，Yb，Lu）中存在丰富的非常规费米子。结果表明，当不考虑自旋轨道耦合（SOC）时，这些化合物的电子能带结构在费米能级附近存在二次色散三重点（TP）、线性色散四重点（FP）和六重点（SP）.值得注意的是，FP是电荷为2的Dirac-like点。更重要的是，在化合物Re 2 C 3中，化合物Yb 2 C 3具有非常干净的能带结构，其非常规费米子接近费米能级。我们还发现，单轴应变可以将非常规费米子转变为其他类型的费米子，这取决于应变的方向。当考虑SOC时，SP变换到八次退化点和四次退化点。总之，我们的工作提供了一个家庭的现实材料来研究非常规费米子。
英文摘要：
Unconventional fermions, such as three-fold, four-fold, six-fold, and eight-fold fermions have attracted intense attention in recent years. However, the concrete materials hosting unconventional fermions are still in urgent scarcity. In this work, based first-principle calculations and symmetry analysis, we reveal rich unconventional fermions in existing compound Re2C3 (Re = Y, La, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Tm, Yb, Lu). We show that these compounds host quadratic dispersive three-fold (TP), linear dispersive four-fold (FP) and six-fold points (SP) near the Fermi level in their electric band structures when spin-orbital coupling (SOC) is not included. Notably, the FP is charge-2 Dirac-like point. More importantly, among compound Re2C3, the compound Yb2C3 has very clean band structure, and its unconventional fermions are closed to the Fermi level. We also find that a uniaxial strain can transform the unconventional fermions into other types fermions, depending on the directions of strain. When SOC is considered, a SP transform to an eightfold degenerate point and a fourfold degenerate point. Overall, our work provides a family of realistic materials to study the unconventional fermions.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
