鐵氧化合物(SrFeO3-δ)電荷有序結構的X光散射研究

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Title:	鐵氧化合物(SrFeO3-δ)電荷有序結構的X光散射研究
Other Titles:	Study of the charge ordering in SrFeO3-δ using X-ray scattering
Authors:	陳榮富;Chen, Jung-Fu
Contributors:	淡江大學物理學系碩士班杜昭宏;Du, Chao-Hung
Keywords:	磁阻現象;SrFeO3-δ;硬X光;電荷調制結構;Magnetoresistance;Hard X-ray;Charge modulation
Date:	2012
Issue Date:	2013-04-13 11:02:48 (UTC+8)
Abstract:	本研究是利用X光散射以及電性與磁性量測來研究鐵基氧化物SrFeO3-δ(2.5<3-δ<3)的傳輸行為、調制結構與磁阻現象(MR)。在磁性的量測中，發現在溫度約為70 K時磁化率會急劇的下降，在低溫表現出反鐵磁相的行為；在電性的量測中，當溫度小於TCO ≈ 110 K時，電阻率開始呈現非線性的變化，且在低溫時表現出高電阻率，而且在60 K附近有熱滯現象的發生。利用X光散射，我們發現此異常的傳輸行為是跟電荷及電子自旋所形成的有序排列結構、及此調制結構所引起的晶格形變有關。此結果可用於了解鐵基氧化物SrFeO3-δ的磁阻現象。 We report the study of the magnetoresistance behavior and the charge/spin modulations in a high quality single crystal of SrFeO3-δ using magnetization, conductivity, and x-ray scattering. The crystal displays a sharp magnetic transition at T ≈ 60 K and a nonlinear conductivity behavior at about T ≈ 110 K, suggesting a 3-δ of about 2.81. In addition, there exists the hysteresis phenomenon with a transition width of about 10 K at T ≈ 60 K. A charge modulation was located at (0, 0, L ± q), q ≈ 0.36 to have a transition temperature of T ≈ 110 K by the use of x-ray scattering with x-ray energy of 10 keV and 12 keV. This is in accord with the nonlinear transport transition as observed by conductivity measurement. By the means of resonant soft x-ray diffraction around the Fe L-edge, we also observed the spin modulation (from paramagnetic to antiferromagnetic states) in agreement with the formation of spin ordering doubling the c-axis.
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