在本論文中，我們利用軟X光的共振散射方法來研究純金屬鉻的電荷密度波相變。使用一般的X光會使接收到的散射訊號太弱而無法研究電荷密度波的重要細節，因此藉由L_2與L_3-edge的共振效應可以增強電荷密度波的散射訊號，幫助我們了解電荷密度波相變的性質與費米面附近的電子行為。純金屬鉻的電荷密度波調制波向量Q_CDW≈(0.09 0 0)。首先，我們將光源變換成水平與垂直兩種不同的極化方向來觀察電荷密度波隨能量的變化。之後將極化方向固定為水平方向並改變溫度觀察電荷密度波隨溫度的變化。最後我們量測布拉格繞射峰隨溫度的變化來研究自旋翻轉與晶格形變的關係。

In this study, we have demonstrated that CDW modulation in Cr can be probed using soft x-ray scattering. Because of the very weak signal from the satellite reflections caused by the formation of CDWs, it is difficult to undertake the detailed studies of CDWs with non-resonant x-ray scattering. However, with the help of resonant x-ray scattering, diffraction signals from weak satellite reflections could be largely enhanced. The wavelength λCDW was observed to have ~10a (a：lattice parameter of Cr) and Q_CDW≈(0.09 0 0) along [100] direction, and we obtained resonant enhancement of the signal near L2 and L3 edges. We  studied the CDW peak at both of π and σ channels at T=77K and the temperature dependence between 70K and 300K at π channel.We also studied the temperature dependence of the Bragg peak.

目錄
第一章 序論.........................	1
第二章 共振X光散射原理..............	4
2.1 布拉格定律......................	4
2.2 軟X光的共振散射.................	5
第三章 電荷密度波與自旋密度波簡介...	10
3.1 相變............................	10
3.2 Mott Insulator..................	11
3.3 電荷密度波......................	13
3.4 自旋密度波......................	16
第四章 樣品準備與實驗方法...........	19
4.1 樣品特性與結構	..................19
4.2 實驗儀器簡介....................	23
4.2.1 In-house實驗器材..............	23
4.2.2 橢圓偏極聚頻磁鐵(EPU)光束線...	25
4.3實驗方法及步驟...................	29
第五章 實驗結果與分析...............	32
5.1 電荷密度波的電子組態............	32
5.2 電荷密度波繞射峰與能量之關係....	37
5.3 電荷密度波與溫度變化之分析......	41
5.4 布拉格繞射峰與溫度變化之分析....	43
第六章 結論.........................	48
參考文獻............................	50

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