通过光电子能谱探测Ta2NiSe5中的激子绝缘体状态。
Excitonic insulator state in Ta2NiSe5 probed by photoemission spectroscopy.
作者信息
Wakisaka Y, Sudayama T, Takubo K, Mizokawa T, Arita M, Namatame H, Taniguchi M, Katayama N, Nohara M, Takagi H
机构信息
Department of Physics, University of Tokyo, Kashiwa, Chiba 277-8561, Japan.
出版信息
Phys Rev Lett. 2009 Jul 10;103(2):026402. doi: 10.1103/PhysRevLett.103.026402.
We report on a photoemission study of Ta2NiSe5 that has a quasi-one-dimensional structure and an insulating ground state. Ni 2p core-level spectra show that the Ni 3d subshell is partially occupied and the Ni 3d states are heavily hybridized with the Se 4p states. In angle-resolved photoemission spectra, the valence-band top is found to be extremely flat, indicating that the ground state can be viewed as an excitonic insulator state between the Ni 3d-Se 4p hole and the Ta 5d electron. We argue that the high atomic polarizability of Se plays an important role to stabilize the excitonic state.
我们报道了对具有准一维结构和绝缘基态的Ta2NiSe5的光电子能谱研究。Ni 2p芯能级光谱表明，Ni 3d子壳层部分占据，且Ni 3d态与Se 4p态强烈杂化。在角分辨光电子能谱中，发现价带顶极其平坦，这表明基态可被视为Ni 3d-Se 4p空穴与Ta 5d电子之间的激子绝缘态。我们认为Se的高原子极化率对稳定激子态起着重要作用。
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