STUDY OF SRCOO3?? ELECTRONIC STRUCTURE USING DENSITY FUNCTIONAL THEORY

• Main Author: Wilbert, Kevin
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/70691
• Institution: Institut Teknologi Bandung

In this final project, the electronic structure of thin film and bulk systems for SrCoO2.5 and SrCoO3.0 have been calculated, along with the effect of electric field disturbances using the density functional theory (DFT) method. The bulk crystal structures with oxygen concentrations of 2.5 (O2.5) and 3 (O3.0) were created using the bulk structure based on experimental results, while the thin film crystal structure is a modified bulk crystal structure with the addition of a vacuum structure. The crystals used for Oxygen concentrations 3.0 and 2.5 are cubic perovskite with space group Pm3m and brownmillerite with space group Ima2, respectively. Both structures were optimized through the structural relaxation process. In the calculation, the correlation effect of the 3d orbitals of Co atoms was reviewed using the Hubbard parameter ????. The calculation results of the system bulk O3.0 system obtains the ferromagnetic conductor ground state with the Co high spin orbital state configuration, while the O2.5 system obtains the antiferromagnetic insulator ground state with the Co high spin orbital state configuration. The insulator state results from the shift of O 2p and Co 3d suborbital away from Fermi energy. The application of an electric field to SrCoO2.5 and SrCoO3.0 thin films does not change the density of states of each system, but results in different energy changes. A decrease in energy is observed in SrCoO3.0 and SrCoO2.5 thin film due to the application of positive and negative electric fields, with a difference in the maximum point of energy shifted to the positive electric field for the thin film of SrCoO2.5.