Non-excitonic mechanism for electronic and structural phase transitions in Ta2Ni(Se,S)5

Year: 2025

Type: preprint

Abstract: We present a first-principles study based on density functional theory (DFT) on the electronic and structural properties of Ta2NiSe5, a layered transition metal chalcogenide that has been considered as a possible candidate for an excitonic insulator. Our systematic DFT results however provide a non-excitonic mechanism for the experimentally observed electronic and structural phase transitions in Ta2NiSe5, in particular explaining why sulfur substitution of selenium reduces the distortion angle in the low-temperature phase and potassium dosing closes the gap in the electronic structure. Moreover, the calculations show that these two effects couple to each other. Further, our first-principles calculations predict several changes in both the crystal structure and electronic structure under the effects of uniform charge dosing and uniaxial strain, which could be tested experimentally.

Source: arXiv (Cornell University)

Authors: Tang, Weichen, Li, Zhenglu, Chen, Cheng, He, Yu, Louie, Steven G.

Institutions: Lawrence Berkeley National Laboratory, University of California, Berkeley, Yale University, University of Oxford

Language: English

Topic: 2D Materials and Applications

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

Open Access status: green

Funders: National Science Foundation, U.S. Department of Energy, National Energy Research Scientific Computing Center, Office of Science, Division of Materials Research, Office of Advanced Cyberinfrastructure, Basic Energy Sciences, Lawrence Berkeley National Laboratory

OpenAlex ID: W6979350529