磷摻雜對鐵基超導材料LaOFeAs1-xPx中電子分佈的影響;Effects of phosphorus doping on the electronic charge distribution in Iron-base superconducting material LaOFeAs1-xPx

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题名:	磷摻雜對鐵基超導材料LaOFeAs1-xPx中電子分佈的影響;Effects of phosphorus doping on the electronic charge distribution in Iron-base superconducting material LaOFeAs1-xPx
作者:	戴士傑;Tai, Shih-Chieh
贡献者:	物理學系
关键词:	超導;電子雲圖
日期:	2017-07-25
上传时间:	2017-10-27 13:41:32 (UTC+8)
出版者:	國立中央大學
摘要:	本篇論文討論的鐵基超導材料LaOFeAs1-xPx ( x =0.4、0.48)，是以不同比例的磷原子摻雜於無超導性的材料LaOFeAs中而構成。根據陳樹希學長的碩士論文，我們發現其磁性行為、磁有序參數、磁結構及超導特性等。以固態反應法製備樣品，並以X光繞射儀判定其結構，再研究其電子分佈的狀況。在常溫下比較，我們藉由電子雲圖能發現，隨磷摻雜比例的提升，鐵離子附近的電子會隨之增加，而在已知 x = 0.48相較 x = 0.4有較大的磁化強度的前提下，我們用液態氦將樣品降溫至3K，觀察到在過渡超導溫度前後，具有較明顯鐵磁性的 x = 0.4的電子分佈在La-O層和As/P-Fe層之間較分散。最後從 x = 0.48的M(T)曲線圖發現在210K時，磁化率趨於平緩，表示其有可能有鐵磁性，因此從電子雲圖也觀察到其電子分佈有其特殊之處，與其他電子雲圖察到的差異甚大。 ;We study a kind of iron-base superconductor material LaOFeAs1-xPx ( x =0.4,0.48). This material is composed of different fraction phosphorus and LaOFeAs which is not superconducting material. Depend on the master’s thesis written by Shu-Shi, Chen. Sample was made by solid reaction and magnetic behavior, order parameter, magnetic structure, superconductivity and so on are studied. Crystal structure is tetragonal, space group is P4/nmm determined by X-ray diffraction and it is layer structure which composed of La2O2 and Fe2As2. Under the room temperature, we found that when increasing the doping amount of phosphorus, electrons would come closer to the iron-ion by the electron density map. In order to check the difference through the TC, we used the liquid helium to make the samples cooling down to low temperature (3K). Then we discovered the electrons distribution between La-O layers and As/P-Fe layers, the fraction x = 0.4, was more dispersed than the other. Finally, according to the M(H) curve graph we found the special case at 210K, it might have the ferromagnetic component. And it’s electrons distribution is special and different from others.
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