Type-II Dirac fermions in the PtSe2 class of transition metal dichalcogenides
Type-II Dirac fermions in the PtSe2 class of transition metal dichalcogenides
复制标题
PtSe2 类过渡金属二硫属化物中的 II 型狄拉克费米子
DOI：
10.1103/physrevb.94.121117
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发表时间：
2016-09-27
影响因子：
3.7
通讯作者：
Duan, Wenhui
中科院分区：
文献类型：
--
作者：
Huang, Huaqing;Zhou, Shuyun;Duan, Wenhui
最近，在电子和空穴袋在孤立的外尔点接触的新物质相中发现了一种新的“II型”外尔费米子，它表现出奇异的现象，例如角度相关的手征异常[Nature（伦敦）527，495（2015）]。这就提出了一个有趣的问题，即它的对应物，第二类狄拉克费米子存在于真实的材料中。在这里，我们预测的存在下，在一类过渡金属二硫属化物材料的双保护的II型狄拉克费米子。我们对PtSe2的第一性原理计算揭示了它的体II型狄拉克费米子，其特征在于强烈倾斜的狄拉克锥，新颖的表面态，和异国情调的掺杂驱动的Lifshitz转变。我们的研究结果表明，PtSe2型材料中第二类狄拉克费米子的存在与其在棒m1上的结构P（3）对称性密切相关，这为第二类狄拉克费米子的实验实现提供了有益的指导，并提供了不同于已知标准狄拉克费米子的有趣物理性质.
Recently, a new "type-II" Weyl fermion, which exhibits exotic phenomena, such as an angle-dependent chiral anomaly, was discovered in a new phase of matter where electron and hole pockets contact at isolated Weyl points [Nature (London) 527, 495 (2015)]. This raises an interesting question about whether its counterpart, i.e., a type-II Dirac fermion, exists in real materials. Here, we predict the existence of symmetry-protected type-II Dirac fermions in a class of transition metal dichalcogenide materials. Our first-principles calculations on PtSe2 reveal its bulk type-II Dirac fermions which are characterized by strongly tilted Dirac cones, novel surface states, and exotic doping-driven Lifshitz transition. Our results show that the existence of type-II Dirac fermions in PtSe2-type materials is closely related to its structural P (3) over bar m1 symmetry, which provides useful guidance for the experimental realization of type-II Dirac fermions and intriguing physical properties distinct from those of the standard Dirac fermions known before.