研究目的
Investigating the evolution of the electronic structure across the metal–insulator transition in epitaxial LaNiO3 films of varying thicknesses.
研究成果
The study reveals a strong dependence of the quasiparticle mean free path on the sample thickness, explaining the absence of quantum-well states in ARPES experiments on nickelate thin films. The similarity between the electronic structures of ultrathin LNO films and insulating NNO suggests an important role of structural relaxation at the interface or surface in the MIT of ultrathin LNO films.
研究不足
The study is limited by the resolution of the ARPES setup and the quality of the thin films. The absence of a clear gap in the insulating state and the unresolved nature of the MIT mechanism are also limitations.
1：Experimental Design and Method Selection
Angle-resolved photoemission spectroscopy (ARPES) was used to study the electronic structure of LaNiO3 thin films. The films were grown in situ by RF magnetron sputtering.
2：Sample Selection and Data Sources
A series of epitaxial LaNiO3 films with thicknesses ranging from 19 u.c. to 2 u.c. were grown on LAO (001) substrates.
3：List of Experimental Equipment and Materials
RF magnetron sputtering system, electron spectrometer from MB Scientific, 11-eV pulsed laser from Lumeras, Philips X’Pert 1 diffractometer.
4：Experimental Procedures and Operational Workflow
Films were grown at ≈500°C and pressure P = 0.18 mbar in a mixed 7:2 Ar:O2 atmosphere. After growth, films were transferred in vacuo to the laser-ARPES setup. Photoemission experiments were performed with an energy resolution of ≈7 meV and angular resolution of ≈0.003 ??1.
5：Data Analysis Methods
The electronic band dispersion and Fermi surface were analyzed. The mean free path λ of the charge carriers was evaluated as a function of film thickness.
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