no code implementations • 15 Dec 2020 • Q. He, X. Que, L. Zhou, M. Isobe, D. Huang, H. Takagi
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.
Strongly Correlated Electrons Mesoscale and Nanoscale Physics