參雜Ni在Tc於Mg0.06Fe1-xNixTe0.55Se0.45的影響

Effect of Ni-doping on Tc of Mg0.06Fe1-xNixTe0.55Se0.45 Superconductors

張舜程(SHUN-CHENG ZHANG)

指導教授 ： 李文新

國立中正大學/理學院/物理學系/碩士(2016年)

摘要

Fe1+yTe1-xSex之晶體結構具有假穩定(metastable)狀態之性質，亦即當Fe之量稍大於1 (或y > 0 )，即形成四方晶系(tetragonal)結構，而Fe之量稍小於1 ( y < 0 )，卻形成六方晶系(hexagonal)之結構。過去的研究顯示Mg取代多餘的鐵Fe(2)的位置( 晶格常數變動可知是取代Fe(2)非Fe(1))，可以形成tetragonal單相，例如Mg0.1FeTe0.55Se0.45具有四方晶系單相晶體結構，且其超導臨界溫度Tc = 12.5 K。為近一步了解此系統磁性對超導的影響，本研究用Ni取代Fe(1)之位置，並將Mg0.1莫耳比例更改為Mg0.06，可以成功製備做出tetragonal結構單相或接近單相之Mg0.06NixFe1-xTe0.55Se0.45系列樣品，從磁性量測之結果我們發現微量的Ni對 Fe(1)的取代，可以有效的抑制超導訊號， 2% (x= 0.02)的取代量，便可以使Mg0.06Ni0.02Fe0.98Te0.55Se4.45相對於Mg0.06FeTe0.55Se0.45就只剩極弱的超導訊號，Tc也降到4.2 K；到了x = 0.03，即3%的取代時，在我們實驗儀器量測極限T > 1.8 K時，順磁已經完全大過超導訊號。此結果說明了Fe(1)之有序排列對維持FeTe1-xSex超導具有很重要的關係。

關鍵字:超導體

關鍵字

超導體

並列摘要

Fe1 +yTe1-xSex nature of having a false stable (metastable) state it, that is, when the amount of Fe slightly greater than 1 (or y> 0), that the formation of tetragonal system (tetragonal) structure, but it is slightly less than the amount of Fe 1 (y <0), but the structure of the hexagonal (hexagonal) of the formation. Past studies have shown that Mg substituted excess iron Fe (2) position (lattice constant change seen is substituted Fe (2) Non-Fe (1)), can be formed tetragonal single phase, for example having a tetragonal Mg0.1FeTe0.55Se0.45 single-crystal phase crystal structure, and its superconducting critical temperature Tc = 12.5 K. A closer understanding of the impact of the superconducting magnetic system, the study of Ni substituted Fe (1) of the position and Mg0.1 mole ratio changed to Mg0.06, can be successfully prepared to make a tetragonal structure at or near single-phase Mg0.06NixFe1-xTe0.55Se0.45 series single-phase samples, the results from the measurement of the magnetic we found Fe (1) substituted a trace amount of Ni, can effectively suppress the superconductivity signal, 2% (x = 0.02) of substitution, we can make Mg0.06Ni0.02Fe0.98Te0.55Se4.45 respect Mg0.06FeTe0.55Se0.45 left with a very weak superconductivity signal, Tc also dropped to 4.2 K; the x = 0.03, or 3 substituents% in our experiment instrument measurement limit T> 1.8 K, the paramagnetic has been completely large superconducting signal. This result shows the Fe (1) for the maintenance of an ordered arrangement FeTe1-xSex superconductivity has a very important relationship.

Keyword:superconductor

並列關鍵字

superconductor

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