電荷密度波之軟X光共振散射研究

Resonant Soft X ray Scattering of Charge-density-wave Study in Chromium

廖尹駿(Yin-Jiun Liao)

指導教授 ： 杜昭宏

淡江大學/理學院/物理學系碩士班/碩士(2009年)

https://doi.org/10.6846/TKU.2009.00233

摘要

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。

關鍵字

軟X光共振散射 ； 電荷密度波相變

並列摘要

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.

並列關鍵字

Resonant Soft X-ray Scattering ； CDW

參考文獻

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