【摘要】：磁各向異性是磁性薄膜最重要的基本特征之一,它的強度決定了磁性薄膜的自然共振頻率。利用傳統(tǒng)的調(diào)控方法產(chǎn)生一個方向確定的靜態(tài)磁各向異性。若該薄膜用于高頻磁性器件時則表現(xiàn)出明顯的方向性,當微波磁場偏離磁各向異性的垂直方向時,器件則無法達到最佳性能。然而,利用條紋磁疇的轉(zhuǎn)動磁各向異性可以解決高頻電子器件方向性的問題。本論文研究了多晶NiFe磁性薄膜、非晶CoFeB磁性薄膜的制備工藝參數(shù)對條紋磁疇結(jié)構及其磁性能的影響規(guī)律。并為了滿足電子器件柔性化的發(fā)展需求,利用具有超彈性的聚二甲基硅氧烷襯底結(jié)合傾斜濺射與襯底預應變研究了柔性褶皺薄膜的表面形貌、靜態(tài)及動態(tài)磁性能。首先,通過磁控濺射生長多晶的NiFe磁性薄膜,系統(tǒng)地研究了NiFe薄膜的厚度、濺射功率密度、濺射氣壓等制備工藝參數(shù)對條紋磁疇結(jié)構、面內(nèi)靜態(tài)磁各向異性、面內(nèi)轉(zhuǎn)動磁各向異性、垂直磁各向異性的影響規(guī)律。研究發(fā)現(xiàn),高濺射功率密度可以降低薄膜出現(xiàn)條紋磁疇的臨界厚度。NiFe薄膜的斷面結(jié)構表明柱狀晶的形成是表現(xiàn)出條紋磁疇結(jié)構的本質(zhì)原因,高功率密度下低濺射氣壓有利于柱狀晶結(jié)構的形成,表現(xiàn)出規(guī)整的條紋磁疇結(jié)構,高濺射氣壓會導致柱狀晶纖細化,面內(nèi)轉(zhuǎn)動磁各向異性與面外垂直磁各向異性增強,條紋磁疇結(jié)構變得混亂。其次,利用傾斜磁控濺射的方法制備了非晶CoFeB磁性薄膜,并研究了通過改變傾斜濺射的角度對非晶CoFeB薄膜的磁疇結(jié)構、面內(nèi)磁各向異性及其垂直磁各向異性的影響,并對非晶薄膜出現(xiàn)條紋磁疇結(jié)構的原因進行了分析。傾斜濺射可以誘導非晶的CoFeB薄膜出現(xiàn)條紋磁疇結(jié)構,并且隨著傾斜角度的逐漸增大,薄膜的面內(nèi)磁各向異性與垂直磁各向異性均呈現(xiàn)增加的趨勢。通過對傾斜生長的薄膜進行斷面結(jié)構分析,結(jié)果表明正是由于薄膜具有傾斜柱狀結(jié)構的形狀各向異性,從而導致薄膜的面內(nèi)磁各向異性與垂直磁各向異性均顯著增加。最終,利用具有超彈性的聚二甲基硅氧烷襯底研究了傾斜磁控濺射與襯底預應變對FeCoTa柔性褶皺薄膜的表面形貌、靜態(tài)與動態(tài)磁性能的影響。在預拉伸的PDMS襯底上生長非磁性Ta釋放拉伸后誘導形成表面呈現(xiàn)符合正弦函數(shù)的褶皺條紋結(jié)構。然后垂直于褶皺條紋方向傾斜濺射FeCoTa磁性薄膜,由于表面的褶皺條紋增強了傾斜濺射的自遮擋效應從而導致柔性磁性薄膜單軸各向異性和共振頻率的增加。在柔性FeCoTa磁性薄膜中通過增大傾斜濺射角度與襯底預應變可以增強薄膜的單軸磁各向異性,從而致使薄膜的磁化機制偏向于疇壁形核。
[Abstract]:Magnetic anisotropy is one of the most important basic characteristics of magnetic thin films. Its intensity determines the natural resonance frequency of magnetic thin films. Traditional control methods are used to generate a directional static magnetic anisotropy. If the film is used in high frequency magnetic devices, it shows obvious directionality, and when the microwave magnetic field deviates from the vertical direction of magnetic anisotropy, the device can not achieve the optimal performance. However, the directional problem of high frequency electronic devices can be solved by using the rotational magnetic anisotropy of stripe domain. In this paper, the influence of the preparation process parameters of polycrystalline NiFe magnetic thin films and amorphous CoFeB magnetic thin films on the stripe domain structure and magnetic properties has been studied. In order to meet the development of flexibility of electronic devices, the surface morphology, static and dynamic magnetic properties of flexible pleated films were studied by using the superelastic polydimethylsiloxane substrate combined with slant sputtering and substrate pre-strain. Firstly, polycrystalline NiFe magnetic thin films were grown by magnetron sputtering. The thickness, sputtering power density and sputtering pressure of NiFe thin films were systematically studied to determine the stripe domain structure and in-plane static magnetic anisotropy. The effect of rotating magnetic anisotropy and vertical magnetic anisotropy in plane. It is found that high sputtering power density can decrease the critical thickness of stripe domain. The sectional structure of nife thin film shows that the columnar crystal formation is the essential reason for the stripe domain structure. Low sputtering pressure at high power density is favorable to the formation of columnar crystal structure, showing regular stripe domain structure. High sputtering pressure will result in the columnar crystal becoming fine, and the in-plane rotation magnetic anisotropy and the out-of-plane vertical magnetic anisotropy will be enhanced. The stripe domain structure becomes chaotic. Secondly, amorphous CoFeB magnetic thin films were prepared by inclined magnetron sputtering. The effects of the angle of tilt sputtering on the magnetic domain structure, in-plane magnetic anisotropy and perpendicular magnetic anisotropy of amorphous CoFeB films were studied. The reason of stripe domain structure in amorphous thin films was analyzed. Tilt sputtering can induce stripe domain structure in amorphous CoFeB films, and the in-plane magnetic anisotropy and vertical magnetic anisotropy of amorphous CoFeB films increase with the increasing of tilt angle. The results show that the in-plane magnetic anisotropy and perpendicular magnetic anisotropy of the films are significantly increased due to the shape anisotropy of the tilted columnar structure. Finally, the effects of inclined magnetron sputtering and substrate prestrain on the surface morphology, static and dynamic magnetic properties of FeCoTa flexible fold films were investigated by using polydimethylsiloxane substrates with hyperelastic properties. Non-magnetic Ta was grown on pre-stretched PDMS substrate, and the surface was induced to form a fold stripe structure with a sinusoidal function after releasing and stretching. Then inclined sputtering FeCoTa magnetic thin films perpendicular to the direction of fold stripes. Due to the enhancement of the self-occlusion effect of slanting sputtering the uniaxial anisotropy and resonance frequency of the flexible magnetic thin films are increased due to the wrinkle stripes on the surface. The uniaxial magnetic anisotropy of flexible FeCoTa films can be enhanced by increasing the angle of oblique sputtering and the substrate prestrain, which results in the magnetization mechanism of the films being biased towards the domain wall nucleation.
【學位授予單位】：湘潭大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB383.2

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相關期刊論文 前2條

1 Xuemeng Han;Jinhua Ma;Zhen Wang;Yalu Zuo;Li Xi;;In-plane Uniaxial Anisotropy and Magnetization Reversal Mechanism of FeCo Films by Strip Pattern[J];Acta Metallurgica Sinica(English Letters);2014年06期

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本文編號：2226138