ray linear dichroism for Sr3Cr2O8、CoO、Co(NO3)2 and SrCuO2
| Autor: | Wang, Yu-Chieh, 王煜傑 |
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| Rok vydání: | 2016 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 104 We utilized synchrotron radiation linear polarized light to explore Sr3Cr2O8, CoO, Co (NO3)2 and SrCuO2 for its orbital ordering and electronic structure. In this thesis, Sr3Cr2O8 and CoO projects are supervised by Dr. Chun-fu Chang of Max Planck Institute, Dresden, Germany. For Sr3Cr2O8, we used linear polarized x-ray to measure the single-crystal sample for Cr L-edge absorption spectra to explore the chromium electronic structure and spin dimers formation, and Jahn - Teller Distortion. Along with the multiplet theory, we find the ground state wave functions, orbital ordering, as well as the electronic structure for Sr3Cr2O8. We also study cobalt oxide and cobalt nitrate using linear polarized light of Co L-edge x-ray absorption spectroscopy and deploy theoretical calculations in order to analyze the spectra. In the case of cobalt oxide, we use extendable substrate MICA in order to investigate the effect of the strain influence on the thin films. However, from the results, it seems that the mechanism for CoO growth on MICA is only related to Van deel war force. In the Co(NO3)2, cobalt ions have two different sites, which is divided by the way they are distorted. Assisted by the theoretical calculations, we find out that even the cobalt ions are in different local structure, they still show a total spin of 3 / 2 as the purely high-spin state. In addition, we also focus on SrCuO2. We want to investigate how the thickness of SrCuO2 influences the crystal field. It is an essential element for shaping superconductivity. Our result indicates that if the thickness is thinner than 10 unit cells, it grows in chain-like structure; while above 10 unit cells, it become plane-like structure leading to superconductivity with appropriate doping. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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