Browsing by Author "Chou, Hsiung"

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Effects of strain on the electronic structures and T-C's of the La0.67Ca0.33MnO3 and La0.8Ba0.2MnO3 thin films deposited on SrTiO3
(2006-08-21)
Chou, Hsiung
;
Tsai, M. -H.
;
Yuan, F. P.
;
Hsu, S. K.
;
Wu, C. B.
The strain effects on the electronic structures of La0.67Ca0.33MnO3 (LCMO) and La0.8Ba0.2MnO3 (LBMO) thin films have been studied by O K-edge x-ray absorption near edge structure (XANES) spectroscopy. For LCMO, the first-principles calculations reveal that the features in the XANES spectra are associated with hybridized states between O 2p and Mn minority-spin 3d t(2g) and e(g), La 5d/Ca 3d, and Mn 4s/Ca 4p states. An analysis of these features shows that the tensile strain decreases substantially La-O and Ca-O hybridization and T-C for LCMO. For LBMO, the small compressive strain enhances slightly La-O and Ba-O hybridization and T-C. (c) 2006 American Institute of Physics.
Instrument for x-ray absorption spectroscopy with in situ electrical control characterizations
(2013-12-01)
Huang, Chun-Chao
;
Chang, Shu-Jui
;
Yang, Chao-Yao
;
Chou, Hsiung
;
Tseng, Yuan-Chieh
We report a synchrotron-based setup capable of performing x-ray absorption spectroscopy and x-ray magnetic circular dichroism with simultaneous electrical control characterizations. The setup can enable research concerning electrical transport, element-and orbital-selective magnetization with an in situ fashion. It is a unique approach to the real-time change of spin-polarized electronic state of a material/device exhibiting magneto-electric responses. The performance of the setup was tested by probing the spin-polarized states of cobalt and oxygen of Zn1-xCoxO dilute magnetic semiconductor under applied voltages, both at low (similar to 20 K) and room temperatures, and signal variations upon the change of applied voltage were clearly detected. (C) 2013 AIP Publishing LLC.