有机狄拉克电子体系α-（BEDT-TSeF）$_2$ I $_3$的输运性质
Transport properties of organic Dirac electron system α-(BEDT-TSeF)$_2$I$_3$
摘要：
基于$α$ -（BEDT-TSeF）$_2$ I $_3$在低温下的绝缘行为（$T$ 's），我们首先基于常压下30 K的晶体结构数据进行了第一性原理计算，并利用最大局域Wannier函数构建了一个二维有效模型。作为绝缘行为的可能原因，我们通过使用Hartree近似和$T$ -矩阵近似研究电子状态和输运系数，研究了原位库仑相互作用$U$和自旋轨道相互作用（SOI）的影响。在有限$T$上的计算表明，由于在位库仑相互作用，出现了自旋有序的大质量狄拉克电子（SMD）。我们有兴趣在$α$ -（BETS）$_2$ I $_3$中存在SMD相时，与$U$和SOI的异常竞争效应，并且我们研究了这些对电子状态和电导率的贡献。SMD不是常规的自旋序，但它表现出自旋谷霍尔效应。直流电阻率在自旋有序间隙的存在下增加发散，并表现出负的磁电阻在低$T$区域与减少$T$。电荷密度在出现这种绝缘行为的$T$以下和以上几乎没有变化。然而，当单独考虑SOI时，状态变为拓扑绝缘体相，并且电阻率在相当低的$T$下被边缘传导饱和。当同时考虑SMD和SOI时，SOI抑制了自旋有序能隙，并且在左右狄拉克锥中打开了不同大小的能隙。这种相变导致微波电导率的明显变化，例如不连续跳跃和峰结构。
英文摘要：
Motivated by the insulating behavior of $α$-(BEDT-TSeF)$_2$I$_3$ at low temperatures ($T$'s), we first performed first-principles calculations based on the crystal structural data at 30 K under ambient pressure, and we constructed a two-dimensional effective model using maximally localized Wannier functions. As possible causes of the insulating behavior, we studied the effects of the on-site Coulomb interaction $U$ and spin-orbit interaction (SOI) by investigating the electronic state and the transport coefficient using the Hartree approximation and the $T$-matrix approximation. The calculations at a finite $T$ demonstrated that a spin-ordered massive Dirac electron (SMD) appeared due to the on-site Coulomb interaction. We had an interest in the anomalous competitive effect with $U$ and SOI when the SMD phase is present in $α$-(BETS)$_2$I$_3$, and we investigated these contributions to the electronic state and conductivity. The SMD is not a conventional spin order, but it exhibits the spin-valley Hall effect. Direct current resistivity in the presence of a spin order gap increased divergently and exhibited negative magnetoresistance in the low $T$ region with decreasing $T$. The charge density hardly changed below and above the $T$ at which this insulating behavior appeared. However, when considering the SOI alone, the state changed to a topological insulator phase, and the electrical resistivity is saturated by edge conduction at quite low $T$. When considering both the SMD and the SOI, the spin order gap was suppressed by the SOI, and gaps with different sizes opened in the left and right Dirac cones. This phase transition leads to distinct changes in microwave conductivity, such as a discontinuous jump and a peak structure.
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。
