Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea.
Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea.
Phys Rev Lett. 2019 Nov 15;123(20):206401. doi: 10.1103/PhysRevLett.123.206401.
We demonstrate that the excitonic insulator ground state of Ta_{2}NiSe_{5} can be electrically controlled by electropositive surface adsorbates. Our studies utilizing angle-resolved photoemission spectroscopy reveal intriguing wave-vector-dependent deformations of the characteristic flattop valence band of this material upon potassium adsorption. The observed band deformation indicates a reduction of the single-particle band gap due to the Stark effect near the surface. The present study provides the foundation for the electrical tuning of the many-body quantum states in excitonic insulators.
我们证明了 Ta_{2}NiSe_{5}的激子绝缘体态可以通过带正电的表面吸附物进行电控制。我们利用角分辨光电子能谱的研究揭示了在钾吸附时该材料特征平顶价带在波矢依赖下的有趣变形。观察到的能带变形表明由于表面附近的斯塔克效应导致的单粒子带隙减小。本研究为激子绝缘体态中多体量子态的电调谐提供了基础。
