研究目的
To investigate the role of electron correlations in understanding photoelectron spectroscopy and the Weyl character of MoTe2, specifically how including on-site Coulomb repulsion (Hubbard U) in DFT calculations affects the agreement with experimental data from ARPES and quantum oscillation experiments.
研究成果
Inclusion of a Hubbard U term (around 3 eV) in DFT calculations improves agreement with ARPES and quantum oscillation experiments for γ-MoTe2. It explains polarization dependence in ARPES and angular dependence in quantum oscillations, which pure DFT fails to do. A pair of Weyl points near the Fermi level survives, and the system is near a correlations-induced Lifshitz transition, suggesting potential for experimental probing and further study of Weyl physics interplay.
研究不足
The study relies on computational methods, which may have approximations in DFT and the DFT+U approach. The sensitivity of Weyl points to U values and lattice parameters could lead to uncertainties. Experimental comparisons are based on existing data, and the model may not capture all real-world complexities.
1：Experimental Design and Method Selection:
The study uses density functional theory (DFT) with the DFT+U scheme to incorporate electron correlations via the Hubbard U parameter for Mo 4d states. Spin-orbit coupling (SOC) is included, and calculations are performed using the QUANTUM ESPRESSO software with the PBE exchange-correlation functional. Methods include band structure analysis, Fermi surface visualization, and identification of Weyl points using tools like WANNIER90 and WannierTools.
2：Sample Selection and Data Sources:
The material studied is γ-MoTe2, a type-II Weyl semimetal candidate. Experimental data from ARPES and quantum oscillation experiments are used for comparison.
3：List of Experimental Equipment and Materials:
Computational tools and software are used; no physical equipment is mentioned.
4：Experimental Procedures and Operational Workflow:
Self-consistent DFT calculations are performed with varying U values. Fermi surfaces and band structures are computed and compared to experimental results. Polarization dependence in ARPES is analyzed using symmetry arguments and matrix element calculations.
5：Data Analysis Methods:
Data analysis involves comparing calculated Fermi surfaces and band structures with experimental ARPES and quantum oscillation data. Berry curvature and Weyl point positions are analyzed to understand topological properties.
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