论文标题
通过合金SE从单个绝缘子到激子绝缘子的过渡到单层$ _3 $：一项计算研究
Transition from band insulator to excitonic insulator via alloying Se into Monolayer TiS$_3$: A Computational Study
论文作者
论文摘要
第一原理密度功能理论以及伯特 - 盐分方程计算用于研究单层钛钛二烷核酸钛合金的电子和激子特性，tis $ _ {3-x} $ se $ _x $ _x $（$ _x $（$ x $ = 1和2）。发现带隙和激子结合能表现出对SE代替S的不对称依赖性。而与原始的TIS $ _3 $相比，带隙可以显着降低，而不管SE替代的位置和浓度如何，激子结合能的变化很小。当中央S原子被SE原子取代时，会发现负激子形成能，这表明具有自发的激子冷凝的多体基态。因此，我们的工作为工程激发型绝缘子提供了新的见解。
First-principles density functional theory plus Bethe-Salpeter equation calculations are employed to investigate the electronic and excitonic properties of monolayer titanium trichalcogenide alloys TiS$_{3-x}$Se$_x$ ($x$=1 and 2). It is found that bandgap and exciton binding energy display asymmetric dependence on the substitution of Se for S. While the bandgap can be significantly decreased as compared to that of pristine TiS$_3$, the exciton binding energy just varies a little, regardless of position and concentration of the Se substitution. A negative exciton formation energy is found when the central S atoms are replaced by Se atoms, suggesting a many-body ground state with the spontaneous exciton condensation. Our work thus offers a new insight for engineering an excitonic insulator.
