本文關(guān)鍵詞： 磁性多層膜 垂直磁各向異性 隧穿磁電阻 反�；魻栃� 自旋軌道矩　出處：《北京科技大學》2017年博士論文　論文類型：學位論文

【摘要】：具有納米異質(zhì)結(jié)構(gòu)的磁性薄膜是自旋電子學的核心應用材料。其中,與維度、尺寸密切相關(guān)的表面、界面效應又對材料性能有著至關(guān)重要的影響。本論文著眼于分析鐵磁金屬/氧化物、鐵磁/非磁金屬等異質(zhì)界面對薄膜材料磁性能以及自旋相關(guān)輸運性能的影響;通過實驗測量及表征構(gòu)建界面微結(jié)構(gòu)、界面化學狀態(tài)與材料性能的關(guān)聯(lián);利用界面調(diào)控進一步優(yōu)化材料性能;并探索異質(zhì)結(jié)構(gòu)磁性多層膜的新型自旋邏輯應用。論文主要研究內(nèi)容及成果如下:(1)成功制備出具有垂直磁各向異性的L10-FePt/MgO/L10-FePt單晶外延隧道結(jié)。將界面結(jié)構(gòu)細化至原子終止層尺度,結(jié)合理論計算及界面表征研究了 FePt/MgO界面處不同終止層(Fe或Pt)對隧穿磁電阻的影響。(2)通過變溫及偏壓依賴輸運測量研究了 Fe/MgO/Fe/MgO/Fe單晶外延雙勢壘隧道結(jié)中隨中間Fe層厚度變化的隧穿行為。利用原子分辨的透射電子顯微技術(shù)對Fe層形貌及界面結(jié)構(gòu)進行原位表征,構(gòu)建了動態(tài)演變的界面結(jié)構(gòu)與隧穿行為的關(guān)聯(lián),指出MgO/Fe/MgO界面變化會對輸運通道產(chǎn)生調(diào)制從而影響體系輸運性能。(3)聚焦于鐵磁金屬/氧化物界面化學狀態(tài)對材料性能的影響,利用化學穩(wěn)定的氧化物包覆層以及具有強氧親和能力的界面金屬插層,對無序FePt薄膜、[Pt/Co]3/MgO多層膜以及Ta/CoFeB/MgO/Ta多層膜三種典型材料體系的磁性能及輸運性能進行了調(diào)控:采用SiO2包覆無序FePt超薄膜使其獲得了垂直磁各向異性;在Co/MgO界面處插入優(yōu)化厚度的Ta,[Pt/Co]3/Ta/MgO經(jīng)450℃退火后仍然保持熱穩(wěn)定的垂直磁各向異性和較大的反常霍爾輸出;將Gd插入CoFeB/MgO界面處,在保持垂直磁各向異性的基礎上Ta/CoFeB/Gd/MgO/Ta的有效阻尼因子較之無插層時最多下降70%。(4)基于重金屬/鐵磁金屬/氧化物異質(zhì)結(jié)構(gòu)中自旋軌道矩引起的磁化翻轉(zhuǎn)特性,在具有垂直磁各向異性的Ta/CoFeB/MgO/Ta多層膜中實驗完成了全部16種布爾邏輯運算。更進一步,結(jié)合電壓調(diào)控界面垂直磁各向異性,仿真設計了能夠快速運行16種布爾邏輯運算的三端自旋邏輯器件單元�；谠撛O計思路,實際器件中通過優(yōu)化材料結(jié)構(gòu)可以實現(xiàn)不依賴磁場的邏輯運算功能。未來集成電路中應用這種新型的自旋邏輯器件,有望融合非易失存儲和計算,從而打破當前CMOS工藝以及馮·諾依曼架構(gòu)體系所面臨的發(fā)展瓶頸。
[Abstract]:Magnetic thin films with nanoscale heterostructures are the core applications of spin electronics. The interfacial effect has an important effect on the material properties. In this paper, the effects of ferromagnetic metal / oxide, ferromagnetic / non-magnetic metal and other heterogeneous interfaces on the magnetic properties and spin dependent transport properties of thin film materials are analyzed. The interface microstructure was constructed by experimental measurement and characterization, and the relationship between the chemical state of the interface and the properties of the material was obtained, and the properties of the material were further optimized by the interface control. The main contents and results of this thesis are as follows: 1) the epitaxial tunnel junctions of L10-FePt / MgO / L10-FePt single crystal with perpendicular magnetic anisotropy have been successfully fabricated. The interface structure has been refined to the scale of atomic termination layer. Combined with theoretical calculation and interface characterization, the effects of different termination layers (Fe or PT) at FePt/MgO interface on tunneling magnetoresistance were studied. Atomic resolved transmission electron microscopy (TEM) was used to characterize the morphology and interface structure of Fe layer in situ. The relationship between the dynamic evolution of interface structure and tunneling behavior is constructed. It is pointed out that the change of MgO/Fe/MgO interface will modulate the transport channel and thus affect the transport performance of the system. Using chemically stable oxide coating and interfacial metal intercalation with strong oxygen affinity, The magnetic properties and transport properties of disordered FePt films, [Pt/Co] 3 / MgO multilayers and Ta/CoFeB/MgO/Ta multilayers were regulated. The perpendicular magnetic anisotropy was obtained by using SiO2 coating disorder FePt ultrathin films. At the Co/MgO interface, the optimized thickness Ta, [Pt/Co] 3 / Ta / MgO remains thermally stable perpendicular magnetic anisotropy and large anomalous Hall output after annealing at 450 鈩，

本文編號：1542009