In:
Chinese Physics Letters, IOP Publishing, Vol. 36, No. 10 ( 2019-10-01), p. 107101-
Kurzfassung:
The insulator-metal transition triggered by pressure in charge transfer insulator NiS 2 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.
Materialart:
Online-Ressource
ISSN:
0256-307X
,
1741-3540
DOI:
10.1088/0256-307X/36/10/107101
Sprache:
Unbekannt
Verlag:
IOP Publishing
Publikationsdatum:
2019
ZDB Id:
2040565-0
SSG:
6,25