利用X光散射研究IrTe2中電荷調制結構的一階相變

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Title:	利用X光散射研究IrTe2中電荷調制結構的一階相變
Other Titles:	Study of the first-order phase transition of the charge modulation in IrTe2 using X-ray scattering
Authors:	許家瑋;Hsu, Chia-Wei
Contributors:	淡江大學物理學系碩士班杜昭宏;Du, Chao-Hung
Keywords:	IrTe2;一階相變;抗磁性;電荷調制;遲滯現象;First-order phase transition;Diamagnetism;Charge modulation;Hysteresis
Date:	2016
Issue Date:	2017-08-24 23:38:03 (UTC+8)
Abstract:	本論文利用X光散射與變溫量測實驗方法來研究IrTe2的電荷調制結構相變，IrTe2經由電性量測在 T≈280 K，會有一相變化，且伴隨此相變化的是其晶體結構從室溫的trigonal結構，轉變為低溫相的triclinic。使用X-光散射實驗，我們發現在此相變溫度有一調制結構的產生，此調制結構的波向量為q=1/5(1, 0 , -1)，針對此波向量進行變溫量測，觀察到其結構的相變化為一階相變，經由升溫與降溫量測，也觀察到此相變化的遲滯現象，及遲滯寬度約為3 K。而在磁性量測中，發現與溫度無關的抗磁性在降溫過程中溫度約為275 K時磁化率會急遽的下降，導致更多的抗磁性的行為，且在相變溫度時有熱滯現象的發生，與X光散射強度對溫度的變化一致。經由此一研究，我們了解到IrTe2在T~280K的電性與磁性的相變，是由於晶格的形變所產生的。 We study the phase transition of the single crystal IrTe2 using x-ray scattering. IrTe2 undergoes a metal-insulator transition and a sharp diamagnetic transition at T~280 K, while the crystal structure changes from the trigonal to triclinic phase. Using x-ray scattering, we observed that a modulated structure accompanies with this structural transition. This modulated structure possesses a modulated q-wavevector q ⃑=1/5 (1, 0 , -1). By the means of the temperature dependent measurements, including cooling and warming processes, this modulation shows a first-order transition with a hysteresis width of about 3 K. Measurement on the Bragg reflection also shows the similar behavior. Through this study, we demonstrate that the non-linear transport behavior at T~280 K is coupled with the charge modulation.
Appears in Collections:	[Graduate Institute & Department of Physics] Thesis

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