Journal
INORGANIC CHEMISTRY
Volume 58, Issue 14, Pages 9036-9042Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.inorgchem.9b00432
Keywords
-
Categories
Funding
- National Key Research and Development Program [2016YFA0300404]
- National Natural Science Foundation of China [11674326, 11874357, U1832141]
- Chinese Academy of Sciences' (CAS) Large-Scale Scientific Facility [U1832141]
- Users with Excellence and Scientific Research Grant of Hefei Science Center of CAS [2018HSC-UE011]
- Key Research Program of Frontier Sciences, CAS [QYZDB-SSW-SLH015]
Ask authors/readers for more resources
An excitonic insulating (EI) state is a fantastic correlated electron phase in condensed matter physics, driven by screened electron-hole interaction. Ta2NiSe5 is an excitonic insulator with a critical temperature (T-C) of 328 K. In the current study, temperature-dependent Raman spectroscopy is used to investigate the phonon vibrations in Ta2NiSe5. The following observations were made: (1) an abnormal blue shift around T-C is observed, which originates from the monoclinic to orthorhombic structural phase transition; (2) the splitting of a mode and two new Raman modes at 147 and 235 cm(-1) have been observed with the formation of an EI state. With the help of first-principles calculations and temperature-dependent X-ray diffraction (XRD) experiments, it is found that the TaSe6 octahedra are frozen and the NiSe4 tetrahedra are greatly distorted below T-C. Thus, it seems that the distortion of NiSe4 tetrahedra plays an important role in the strong electron-phonon coupling (EPC) in Ta2NiSe5, while the strong EPC, coupled with electron-hole interaction, opens the energy gap to form the EI state in Ta2NiSe5.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available