论文标题
激子绝缘子TA $ _2 $ nise $ _5 $中的隧道尖端引起的电荷差距的崩溃
Tunneling-tip-induced collapse of the charge gap in the excitonic insulator Ta$_2$NiSe$_5$
论文作者
论文摘要
通过外部手柄调整多体电子阶段在凝结物质科学中至关重要。可调性反映了基本相互作用，并且可以在相变的关键区域中预期对微小的外部刺激的巨大电气，光学和磁反应。激子绝缘子是相互作用电子的外来阶段之一，是由少量和相等数量的电子和孔之间的库仑吸引力产生的，导致在狭窄的差距半导体/半仪表中自发地形成激子对。最近已经讨论过分层的墨西哥葡萄糖ta $ _2 $ _5 $ _5 $，因为激发差距约为250 meV $ t_c $ = 328 k。朝样品表面的几个埃绳朝向样品表面。崩溃强烈表明，在ta $ _2 $ nise $ _5 $的绝缘状态下，差距的多体性质，与激发态状态的形成一致。我们认为，间隙的崩溃主要是由尖端的接近性和产生型绝缘子的载体载体引起的静电电荷积累所驱动的。我们的结果建立了基于激子绝缘子的新型相变函数。
Tuning many-body electronic phases by an external handle is of both fundamental and practical importance in condensed matter science. The tunability mirrors the underlying interactions, and gigantic electric, optical and magnetic responses to minute external stimuli can be anticipated in the critical region of phase change. The excitonic insulator is one of the exotic phases of interacting electrons, produced by the Coulomb attraction between a small and equal number of electrons and holes, leading to the spontaneous formation of exciton pairs in narrow-gap semiconductors/semimetals. The layered chalcogenide Ta$_2$NiSe$_5$ has been recently discussed as such an excitonic insulator with an excitation gap of ~250 meV below $T_c$ = 328 K. Here, we demonstrate a drastic collapse of the excitation gap in Ta$_2$NiSe$_5$ and the realization of a zero-gap state by moving the tip of a cryogenic scanning tunneling microscope towards the sample surface by a few angstroms. The collapse strongly suggests the many-body nature of the gap in the insulating state of Ta$_2$NiSe$_5$, consistent with the formation of an excitonic state. We argue that the collapse of the gap is driven predominantly by the electrostatic charge accumulation at the surface induced by the proximity of the tip and the resultant carrier doping of the excitonic insulator. Our results establish a novel phase-change function based on excitonic insulators.
