Ambient-pressure Dirac electron system in the quasi-two-dimensional molecular conductor α-(BETS)2I3
Ambient-pressure Dirac electron system in the quasi-two-dimensional molecular conductor α-(BETS)2I3
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DOI：
10.1103/physrevb.103.035135
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发表时间：
2021-01-21
影响因子：
3.7
通讯作者：
Sawa, Hiroshi
中科院分区：
文献类型：
--
作者：
Kitou, Shunsuke;Tsumuraya, Takao;Sawa, Hiroshi
本文研究了准二维分子导体α -(BETS)(2)I-3在环境压力下的精确晶体结构和电子态。在T-MI = 50 K时，该分子固体的电子电阻率显示出金属-绝缘体（MI）交叉行为。我们的x射线衍射和C-13核磁共振实验表明，α -(BETS)(2)I-3在T-MI下保持反转对称性。第一性原理计算发现在一般k点有一对各向异性狄拉克锥，在费米能级有简并接触点。该系统绝缘态的起源是由自旋轨道相互作用打开的一个类似于2 meV的小能隙。Z(2)拓扑不变量表明该系统是弱拓扑绝缘子。结果表明，α -(BETS)(2)I-3是研究二维体狄拉克电子系统的理想材料。
We investigated the precise crystal structures and electronic states of a quasi-two-dimensional molecular conductor alpha-(BETS)(2)I-3 at ambient pressure. The electronic resistivity of this molecular solid shows metal-to-insulator (MI) crossover behavior at T-MI = 50 K. Our x-ray diffraction and C-13 nuclear magnetic resonance experiments revealed that alpha-(BETS)(2)I-3 maintains the inversion symmetry below T-MI. First-principles calculations found a pair of anisotropic Dirac cones at a general k point, with the degenerate contact points at the Fermi level. The origin of the insulating state in this system is a small energy gap of similar to 2 meV opened by the spin-orbit interaction. The Z(2) topological invariants indicate that this system is a weak topological insulator. Our results suggest that alpha-(BETS)(2)I-3 is a promising material for studying the bulk Dirac electron system in two dimensions.