本文選題：CoFeB垂直磁化膜　切入點(diǎn)：反常霍爾效應(yīng)　出處：《華中科技大學(xué)》2015年碩士論文

【摘要】：近年來,具有垂直磁各向異性的磁性納米結(jié)構(gòu)由于其優(yōu)秀的特性和廣泛的應(yīng)用領(lǐng)域,逐漸成為國內(nèi)外研究小組的研究熱點(diǎn)。例如,近期有研究小組報(bào)道,在MgO/CoFeB/Ta垂直磁化膜中發(fā)現(xiàn)了巨大的線性反常霍爾電阻;此外,新型的磁性斯格明子磁存儲(chǔ)器件也需要用到垂直磁化薄膜,例如,近期有研究小組在具有垂直磁各向異性的[Co/Pt]N多層膜中發(fā)現(xiàn)了室溫下穩(wěn)定的磁性斯格明子。雖然垂直磁性納米結(jié)構(gòu)已經(jīng)有很多研究,但是還有一些存在的問題沒有闡述清楚。例如,雖然在MgO/CoFeB/Ta垂直磁化膜中發(fā)現(xiàn)了巨大的線性反�；魻栯娮�,但是基于垂直磁化膜反常霍爾效應(yīng)的高靈敏度磁傳感器在低溫下工作的情況目前還很少有研究;另外,盡管學(xué)術(shù)界認(rèn)為基于磁性斯格明子的垂直磁性納米線是非常有應(yīng)用前景的新型磁存儲(chǔ)單元,但是對(duì)于電流和自旋波驅(qū)動(dòng)磁性斯格明子在垂直磁性納米線中的動(dòng)態(tài)過程目前還需要進(jìn)一步研究。本文以具有垂直磁各向異性的納米薄膜和納米線為研究對(duì)象,實(shí)驗(yàn)上通過高真空磁控濺射系統(tǒng)制備薄膜,深入研究了弱局域化作用對(duì)MgO/CoFeB/Ta垂直磁化膜反常霍爾效應(yīng)的影響;同時(shí),本文還通過微磁學(xué)模擬的方法,研究了電流以及自旋波驅(qū)動(dòng)磁性斯格明子在垂直磁性納米線中的動(dòng)態(tài)過程。實(shí)驗(yàn)上,我們通過磁控濺射制備了厚度在1.7 nm~10.5 nm范圍內(nèi)的具有面內(nèi)磁各向異性的CoFeB非晶薄膜,以及CoFeB厚度在0.8 nm~1.4 nm之間具有垂直磁各向異性的MgO/CoFeB/Ta薄膜。繼而,我們測(cè)量了非晶態(tài)CoFeB單層膜以及MgO/CoFeB/Ta垂直磁化膜的低溫電子輸運(yùn)特性。實(shí)驗(yàn)發(fā)現(xiàn),對(duì)于非晶態(tài)CoFeB單層薄膜,當(dāng)薄膜厚度大于3 nm時(shí),邊界跳躍機(jī)制是反�；魻栃�(yīng)的主導(dǎo)機(jī)制,弱局域化作用對(duì)反常霍爾效應(yīng)的影響實(shí)驗(yàn)觀察不到,當(dāng)薄膜厚度小于3 nm時(shí),反�；魻栃�(yīng)由邊界跳躍機(jī)制和斜散射機(jī)制共同產(chǎn)生,并且弱局域化作用對(duì)反常霍爾效應(yīng)的影響可以實(shí)驗(yàn)觀察到;對(duì)于MgO/CoFeB/Ta垂直磁化膜,由于Ta膜層為電子提供了一個(gè)額外的輸運(yùn)通道,弱局域化作用在薄膜的方塊電阻R0大于1.5 k?時(shí)才能觀察到。此外,我們通過微磁學(xué)模擬的方法研究了磁性斯格明子在垂直磁性納米線中移動(dòng)的動(dòng)態(tài)過程。研究發(fā)現(xiàn),磁性斯格明子的尺寸取決于垂直磁性納米線的本征磁學(xué)參數(shù)以及外加磁場(chǎng)的大小,而且,電流驅(qū)動(dòng)磁性斯格明子移動(dòng)的速度與磁性斯格明子的尺寸成正比。其次,磁性斯格明子通過垂直磁性納米線缺陷的閾值電流密度不僅與缺陷的大小有關(guān),還與斯格明子-斯格明子之間的相互作用密切相關(guān)。另外,自旋波也可以驅(qū)動(dòng)磁性斯格明子在垂直磁性納米線中移動(dòng),其移動(dòng)速度與自旋波的頻率、自旋波激發(fā)場(chǎng)大小、以及斯格明子的尺寸密切相關(guān)。
[Abstract]:In recent years, magnetic nanostructures with perpendicular magnetic anisotropy have gradually become the research focus of domestic and foreign research groups because of their excellent properties and wide application fields.For example, a recent team has reported that large linear anomalous Hall resistors have been found in MgO/CoFeB/Ta vertical magnetization films; in addition, new magnetic Schumminon magnetic memory devices need to use perpendicular magnetized films, such as,Recently, a team of researchers found a stable magnetic Schumminon at room temperature in [Co/Pt] N multilayers with perpendicular magnetic anisotropy.Although there have been many studies on perpendicular magnetic nanostructures, there are still some existing problems that have not been clarified.For example, although large linear anomalous Hall resistors have been found in MgO/CoFeB/Ta perpendicular magnetized films, very little research has been done on high sensitivity magnetic sensors based on perpendicular magnetic film anomalous Hall effect at low temperatures.Although the academic community considers magnetic magnetic nanowires based on magnetic Sgrimings to be a promising new magnetic memory cell,However, the dynamic process of magnetic Schumminon driven by current and spin wave in vertical magnetic nanowires needs further study.In this paper, the perpendicular magnetic anisotropy nanocrystalline films and nanowires are studied. The effect of weak localization on the anomalous Hall effect of MgO/CoFeB/Ta perpendicular magnetized films is studied experimentally by a high vacuum magnetron sputtering system.The dynamic processes of current and spin-wave driven magnetic Schumminon in vertical magnetic nanowires are also studied by means of micromagnetics simulation.Experimentally, CoFeB amorphous films with in-plane magnetic anisotropy and CoFeB films with vertical magnetic anisotropy between 0.8 nm~1.4 nm with thickness of 1.7 nm~10.5 nm were prepared by magnetron sputtering.Then we measured the electron transport characteristics of amorphous CoFeB monolayer and MgO/CoFeB/Ta vertical magnetized film at low temperature.It is found that when the thickness of amorphous CoFeB monolayer films is more than 3 nm, the boundary jump mechanism is the dominant mechanism of the anomalous Hall effect, but the effect of weak localization on the anomalous Hall effect is not observed experimentally.When the film thickness is less than 3 nm, the anomalous Hall effect is produced by the boundary jump mechanism and the oblique scattering mechanism, and the effect of weak localization on the anomalous Hall effect can be observed experimentally.Because the Ta film provides an additional transport channel for electrons, weak localization occurs when the sheet resistance R0 of the film is greater than 1.5 k?It is only when you observe it that you can see it.In addition, we study the dynamic process of magnetic Sgrimminon moving in vertical magnetic nanowires by means of micromagnetics simulation.It is found that the size of the magnetic Schumminon depends on the intrinsic magnetic parameters of the vertical magnetic nanowires and the magnitude of the applied magnetic field. Moreover, the speed of the magnetic Schumminon moving by the current drive is proportional to the size of the magnetic Schumminon.Secondly, the threshold current density of magnetic Sgrimminon through vertical magnetic nanowire defects is related not only to the size of defects, but also to the interaction between Sgrimings and Signitons.In addition, the spin-wave can also drive the magnetic Schumminon to move in the vertical magnetic nanowires. Its moving speed is closely related to the frequency of the spin-wave, the magnitude of the spin-wave excitation field, and the size of the spin-minitron.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB383.1

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