玻璃基板粗糙度對於鎳鐵薄膜磁性特性的影響

Abstract

本論文研究鎳鐵薄膜長在不同粗糙度的玻璃基板上的磁性行為。利用氫氟酸蝕刻玻璃的特性，玻璃基板的粗糙度是用氫氟酸的蝕刻時間來控制。在不同粗糙玻璃基板上用磁控式濺鍍成長鎳鐵薄膜(Py/G)。利用原子力顯微鏡來檢視分析平均粗糙度，利用統計方法定量找出各種表貌的相關參數如平均表面粗糙度、方均根粗糙度和偏度。樣品的磁性行為則是用鐵磁共振儀(FMR)和柯爾磁光儀(MOKE)量測得到。實驗使用蓋玻片當作基板，預前處裡是用丙酮經由超音波震盪器清洗，再由15%濃度氫氟酸經不同蝕刻時間來製造不同表面粗糙度，蝕刻完後用去離子水、丙酮同樣用超音波震盪器來清洗，再用氮氣來吹乾基板，最後利用磁控濺鍍鍍上5nm的鎳鐵薄膜。隨著表面蝕刻時間增加，玻璃基板的方均根高度變化並不顯著，最大的方均根高度約為3.75nm最小則是。偏度則和蝕刻時間有正相關。樣品磁性如矯頑場、鐵磁共振吸收半高寬和方均根高度並無明確的關聯。但發現偏度和磁性的相關性，偏度和矯頑場有反V字型的關係圖，最高的矯頑場為20Oe對應到的偏度約為1.5。偏度和鐵磁共振吸收半高寬呈現週期震盪且振幅越來越大週期約為偏度2。

Magnetic properties of NiFe (permalloy, Py) film on glass was studied as function of the roughness of glass substrate. These films were fabricated by Magnetron sputtering on HF etching glass and the thickness of the Py film is fixed 5nm. The roughness was controlled and examined by etching time and AFM, respectively. Cover glass was sed as the substrate which was etched by soaking in 15% HF(Hydrogen Fluoride) solution to produce the roughness. Different states of surface roughness were controlled by the HF etching time up to 15 min. The surface morphology was examined by Atomic force microscopy (AFM), and hence average roughness, root mean square roughness and skewness were obtained for all samples. MOKE was used to measurement the magnetic hysteresis of the sample, while spin dynamics were characterized by a Vector Network Analyzer based ferromagnetic resonance (FMR) spectrometer. Therefore, squareness of hysteresis loop, saturation field, coercivity and damping constant can be analyzed as function of the roughness of Py film.There is no obvious change in root mean square roughness as the etching tike was increased. The minimum and maximum roughnesses were found to 0.25 and 3.75 nm at etching times of 0min and 3mins, respectively. In contrast, skewness was lineally proportional to the etching time. The magnetic properties, such as coercivity, FMR half-line width, have no clearly dependence on root mean square height. However, the dependence of these magnetic parameters on skewness was found. Coercivity showed an inverse V-shpae relationship with increasing skewness that the maximum coercivity of 20Oe is at skewness of 1.5. The FMR resonant field and line width at half maximum height exhibited oscillating behavior as skewness was increased. The periodicity of skewness of this oscillation was about 2.