X-ray absorption spectroscopy on quantum matter: the cases of Ba3V2S4O3, FeSe, K2Mn3(VO4)2(CO3) and Mn2BO4

• Main Authors: Chiang, Jen-Che, 江仁喆
• Other Authors: Lin, Jiunn-Yuan
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/44653835256949276308

碩士 === 國立交通大學 === 物理研究所 === 103 === In cooperation with Zhiwei Hu from Max Planck Institute, this thesis discusses the valence state and electronic structure in cases of Ba3V2S4O3, K2Mn3(VO4)2(CO3), Mn2BO4 and FeSe through the investigation by applying synchrotron radiation on the sample. In this thesis, Ba3V2S4O3 V L-edge is measured by using X-ray absorption near edge spectroscopy (XANES) in order to explore the vanadium valence state at both tetrahedral and octahedral sites. In addition, the measurement is also confirmed by multiplet theoretical calculations through simulating the experimental spectrum. The theoretical calculations suggest that vanadium ions are trivalent and pentavalent in the coordination of V3+S6 and V5+O3S respectively. In the K2Mn3(VO4)2(CO3) case, we measured Mn L-edge by using X-ray absorption near edge spectroscopy (XANES) to explore the spin state in octahedral and trigonal sites. Combined with theoretical calculation, we confirm that the divalent manganese exhibits the high spin state (S=5/2) in both octahedral and trigonal sites. In addition, in order to discuss whether the observation of the electronic structure anisotropy in FeSe caused by nematic order is possible or not under temperature variations, Fe L-edge is measured by using X-ray absorption near edge spectroscopy (XANES) at T=300 K, 105 K, 75 K and 15 K. Although the result shows no evidence of electronic structure anisotropy in Fe L-edge spectrum, the higher quality of FeSe used here than those in literatures makes a better Fe L-edge spectrum available, which leads to the successful verification of the theoretical calculations from literatures. Moreover, we measured Mn K, L-edge XANES spectra in Mn2BO4 to confirm the manganese valence state. The spectrum in both Mn K-edge and L-edge suggests that manganese ions in Mn2BO4 have shown the 1:1 ratios from Mn2+ and Mn3+ in Mn2BO4.