Author:
Wu Hao,Zhou Yong-Hui,Yuan Yi-Fang,Chen Chun-Hua,Zhou Ying,Zhang Bo-Wen,Chen Xu-Liang,Gu Chuan-Chuan,An Chao,Wang Shu-Yang,Qi Meng-Yao,Zhang Ran-Ran,Zhang Li-Li,Li Xin-Jian,Yang Zhao-Rong
Abstract
The insulator-metal transition triggered by pressure in charge transfer insulator NiS2 is investigated by combining high-pressure electrical transport, synchrotron x-ray diffraction and Raman spectroscopy measurements up to 40–50 GPa. Upon compression, we show that the metallization firstly appears in the low temperature region at ∼3.2 GPa and then extends to room temperature at ∼8.0 GPa. During the insulator-metal transition, the bond length of S–S dimer extracted from the synchrotron x-ray diffraction increases with pressure, which is supported by the observation of abnormal red-shift of the Raman modes between 3.2 and 7.1 GPa. Considering the decreasing bonding-antibonding splitting due to the expansion of S–S dimer, the charge gap between the S-ppπ* band and the upper Hubbard band of Ni-3d e
g
state is remarkably decreased. These results consistently indicate that the elongated S–S dimer plays a predominant role in the insulator-metal transition under high pressure, even though the p-d hybridization is enhanced simultaneously, in accordance with a scenario of charge-gap-controlled type.
Subject
General Physics and Astronomy
Cited by
2 articles.
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