本文選題：鈣鈦礦氧化物　切入點(diǎn)：脈沖激光沉積　出處：《南京大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：鈣鈦礦氧化物具有十分豐富的物理和化學(xué)性質(zhì),例如鐵磁性、鐵電性、巨磁阻效應(yīng)等,使其在存儲(chǔ)及傳感等方面都具有廣闊的應(yīng)用前景。因此,引起了廣泛的關(guān)注。本文期望通過(guò)制備幾種鈣鈦礦異質(zhì)結(jié),研究其電、磁特性,探索鈣鈦礦氧化物在存儲(chǔ)方面的應(yīng)用。本文采用脈沖激光沉積技術(shù)制備了CaMnO3/La0.7Sr0.3MnO3,TiO2/LaAlO3,以及SrRuO3/Pr0.8Ca0.2MnO3/SrTiO3(BaTiO3)/La0.7Sr0.3MnO3異質(zhì)結(jié)構(gòu),優(yōu)化了薄膜工藝,測(cè)量了晶體結(jié)構(gòu)、點(diǎn)磁特性,采用微加工手段制備了相關(guān)原型器件并測(cè)試了存儲(chǔ)功能。具體工作包括：(1)在LaA103襯底上沉積了CaMnO3/La0.7Sr0.3MnO3異質(zhì)結(jié)構(gòu),原子力顯微表面形貌測(cè)試表明表面較為平整,X射線衍射結(jié)果表明CaMnO3處于拉應(yīng)力狀態(tài)。壓電力顯微結(jié)果顯示可以在CaMnO3表面用相反的電壓形成約180°的相位襯度,振幅圖上也可以觀察到明顯的疇壁,表明應(yīng)變CaMnO3有可能具有鐵電性。(2)Pt/TiO2/Pt阻變異質(zhì)結(jié)構(gòu)中,通過(guò)在Ti02層和Pt底電極之間加入LaAlO3層,提高了阻變性能。加入30 nm的LaAlO3層后,開(kāi)關(guān)電壓的不穩(wěn)定性得到了有效的抑制,電阻開(kāi)關(guān)比也從102提高到了103。X射線光電子能譜分析表明Ti02層中有大量的氧空位,在外加電場(chǎng)作用下,氧空位能夠遷移到LaAlO3層中形成導(dǎo)電通道。TiO2/LaAlO3異質(zhì)結(jié)高阻態(tài)的阻值隨著LaAlO3層厚度的增加而增大,而低阻態(tài)的阻值則與LaAlO3層厚度無(wú)關(guān),表明了導(dǎo)電細(xì)絲的形成與斷裂優(yōu)先發(fā)生在LaAlO3層中。(3)制備了SrRuO3/Pr0.8Ca0.2Mno3/SrTio3/La0.7Sr0.3MnO3全氧化物自旋過(guò)濾磁隧道結(jié),在外加磁場(chǎng)下,隧道結(jié)呈現(xiàn)出高低兩個(gè)阻態(tài),隧穿磁電阻約為4%。用鐵電BaTiO3代替SrTiO3隧穿層,在SrTiO3襯底上制備了SrTiO3多鐵性隧道結(jié),同時(shí)獲得約1%的隧穿磁電阻和約100%的隧穿電致電阻。
[Abstract]:Perovskite oxides have abundant physical and chemical properties, such as ferromagnetism, ferroelectrics, giant magnetoresistive effect and so on. In this paper, we hope to study the electrical and magnetic properties of perovskite oxides and to explore the application of perovskite oxides in storage by preparing several perovskite heterostructures. In this paper, CaMnO _ 3 / La _ (0.7) Sr _ (0.3) mn O _ (3) O _ (2) / La _ (Alo) _ 3 and SrRuO3/Pr0.8Ca0.2MnO3/SrTiO3(BaTiO3)/La0.7Sr0.3MnO3 heterostructures have been prepared by pulsed laser deposition. The thin film process was optimized, the crystal structure and the point magnetic properties were measured, the related prototype devices were fabricated by microfabrication and the storage function was tested. The specific work includes: 1) depositing the CaMnO3/La0.7Sr0.3MnO3 heterostructure on the LaA103 substrate. The surface morphology of atomic force microscopy shows that the surface is flat and the X-ray diffraction results show that CaMnO3 is in the state of tensile stress, and the PPM results show that the phase contrast can be formed on the surface of CaMnO3 with the opposite voltage about 180 擄. The apparent domain walls can also be observed on the amplitude diagram, which indicates that the strain CaMnO3 may have ferroelectrics. T / TIO _ 2 / Pt resistive variant structure. By adding the LaAlO3 layer between the Ti02 layer and the Pt substrate electrode, the resistance property is improved. After the addition of 30 nm LaAlO3 layer, The instability of switching voltage is effectively suppressed, and the ratio of resistance to switch is increased from 102 to 103. X-ray photoelectron spectroscopy (XPS) analysis shows that there are a lot of oxygen vacancies in the Ti02 layer under the action of an external electric field. The oxygen vacancy can migrate to LaAlO3 layer to form conductive channel. TIO _ 2 / LaAlO _ 3 heterojunction high resistance state increases with the increase of LaAlO3 layer thickness, while the low resistance state resistance value is independent of LaAlO3 layer thickness. The results show that the formation and fracture of conductive filaments preferentially occur in the LaAlO3 layer. The SrRuO3/Pr0.8Ca0.2Mno3/SrTio3/La0.7Sr0.3MnO3 full oxide spin-filtered magnetic tunnel junctions are prepared. The tunneling junctions exhibit high and low resistive states under the external magnetic field. The tunneling magnetoresistance is about 4. Ferroelectric BaTiO3 instead of SrTiO3 tunneling layer is used to fabricate SrTiO3 multiferroelectric tunneling junction on SrTiO3 substrate. At the same time, about 1% tunneling magnetoresistance and about 100% tunneling resistance are obtained.
【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ132.32

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本文編號(hào)：1576240