本文關(guān)鍵詞：磁疇壁結(jié)構(gòu)動(dòng)力學(xué)及其應(yīng)用研究　出處：《蘭州大學(xué)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 磁疇壁 斯格明子 自旋轉(zhuǎn)移矩效應(yīng) 自旋納米振蕩器 賽道存儲(chǔ)器 自旋波

【摘要】：自旋電子學(xué)將電子的自旋屬性和電荷屬性緊密地聯(lián)系了起來(lái),這兩個(gè)自由度的結(jié)合為開(kāi)發(fā)性能優(yōu)異的電子器件提供了更廣闊的空間。賽道存儲(chǔ)器,自旋納米振蕩器,STT-MRAM就是其中三種典型的自旋電子學(xué)器件,有著巨大的應(yīng)用前景,然而在實(shí)現(xiàn)應(yīng)用之前仍有一些問(wèn)題需要解決。本論文主要通過(guò)微磁學(xué)模擬和實(shí)驗(yàn)的手段,針對(duì)賽道存儲(chǔ)器和自旋納米振蕩器等自旋電子學(xué)器件遇到的一些問(wèn)題進(jìn)行研究。(一)賽道存儲(chǔ)器問(wèn)題研究Parkin起初設(shè)計(jì)的賽道存儲(chǔ)器是基于面內(nèi)磁化納米帶中的180度疇壁。相比之下,基于360度疇壁的賽道存儲(chǔ)器具有更高的存儲(chǔ)密度和較強(qiáng)的抗磁場(chǎng)干擾能力。在第三章中,我們首先設(shè)計(jì)了簡(jiǎn)單的產(chǎn)生360度疇壁的電極結(jié)構(gòu)并通過(guò)微磁學(xué)模擬發(fā)現(xiàn),要成功產(chǎn)生360度疇壁,電流脈沖的下降過(guò)程需要緩慢降低以防止疇壁湮滅。然后利用平行納米帶中360度疇壁和180度疇壁的耦合,或者兩個(gè)360度疇壁的耦合提高了360度疇壁的穩(wěn)定性,從而使360度疇壁的極限速度提高了81.1%。第四章中,我們研究了磁振子(自旋波)與360度疇壁的相互作用,自旋波的傳播過(guò)程沒(méi)有電荷輸運(yùn),所以為解決焦耳熱的問(wèn)題提供了一種新的思路。微磁學(xué)模擬研究發(fā)現(xiàn),自旋波也可以驅(qū)動(dòng)360度疇壁運(yùn)動(dòng),而且根據(jù)材料參數(shù)和自旋波頻率的不同,疇壁可以沿著自旋波方向或者反方向運(yùn)動(dòng)。此外,通過(guò)被360度疇壁反射的自旋波研究了自旋波的多普勒效應(yīng)。通過(guò)透射自旋波研究了自旋波的相位移動(dòng)效應(yīng)。垂直各向異性材料納米帶中的疇壁寬度非常窄,而且臨界電流密度也比面內(nèi)磁化樣品中要低,所以非常有利于提高賽道存儲(chǔ)器的存儲(chǔ)密度并降低功耗。產(chǎn)生磁疇壁是研究其應(yīng)用的一個(gè)非常關(guān)鍵的步驟,傳統(tǒng)上是利用一個(gè)與納米帶垂直的直線電極來(lái)產(chǎn)生疇壁。第五章中,我們提出了一個(gè)非常高效的在垂直各向異性納米帶中注入磁疇的Π型的電極結(jié)構(gòu)。這種方法可以用5.35×1011 A/m2的電流脈沖在15 ns的脈沖時(shí)間內(nèi)在Co/Ni多層膜中成功產(chǎn)生一個(gè)磁疇。實(shí)驗(yàn)和計(jì)算結(jié)果都證明這種方法的能耗只有傳統(tǒng)方法的30%左右。最后,我們通過(guò)反�；魻栃�(yīng)測(cè)量了磁疇壁在十字叉結(jié)構(gòu)處的釘扎和脫釘扎現(xiàn)象,并通過(guò)電流對(duì)脫釘扎場(chǎng)進(jìn)行了調(diào)控。(二)自旋納米振蕩器問(wèn)題研究自旋納米振蕩器有很多非常優(yōu)異的性能,然而其輸出功率是一個(gè)瓶頸問(wèn)題,現(xiàn)在有一種非常好的解決思路就是制作振蕩器陣列,然后通過(guò)多個(gè)振蕩器信號(hào)的疊加來(lái)提高輸出功率。第六章中,我們研究了點(diǎn)電流驅(qū)動(dòng)隧道結(jié)結(jié)構(gòu)中磁Skyrmion的振蕩,并依此原理設(shè)計(jì)了一種新型的基于磁Skyrmion的自旋納米振蕩器。該振蕩器可以在一個(gè)器件中同時(shí)輸出多路信號(hào),故而有望提高振蕩器的輸出功率。信號(hào)的線寬可以小于1 MHz。此外,該電極可以在108 A/m2的電流密度下工作且工作頻率最小可以接近0 MHz,最大可以到GHz量級(jí)。
[Abstract]:Spin electronics closely links the spin and charge properties of electrons. The combination of these two degrees of freedom provides a wider space for the development of excellent electronic devices. Spin nanometer oscillator (STT-MRAM) is one of the three typical spin electronics devices, which has a great application prospect. However, there are still some problems to be solved before the application. Some problems encountered by spin electronics devices such as racetrack memory and spin nanometer oscillator are studied. (1). Research on racetrack memory problem Parkin originally designed the racetrack memory based on the 180-degree domain walls in the in-plane magnetized nanobelts. Track memory based on 360-degree domain walls has higher storage density and stronger resistance to magnetic field interference. In Chapter 3. We first designed a simple electrode structure to generate 360-degree domain walls and found that it was necessary to successfully generate 360-degree domain walls by micromagnetic simulation. In order to prevent domain wall annihilation, the current pulse drop process needs to be slowly reduced, and then the coupling of 360 degree domain wall and 180 degree domain wall in parallel nanoribbons is used. Or the coupling of two 360-degree domain walls improves the stability of the 360-degree domain walls, thus increasing the limit speed of the 360-degree domain walls by 81.1. 4th. We study the interaction between magnetic oscillator (spin wave) and 360-degree domain wall. There is no charge transport in the propagating process of spin wave. It provides a new way to solve the problem of Joule fever. The micromagnetic simulation results show that the spin wave can also drive 360 degree domain wall motion, and according to the material parameters and the frequency of spin wave. The domain walls can move either in the spin direction or in the opposite direction. The Doppler effect of spin wave is studied by the reflection of 360 degree domain wall and the phase shift effect of spin wave is studied by transmission spin wave. The width of domain wall in vertical anisotropic nanobelts is very narrow. And the critical current density is lower than that in the in-plane magnetized sample, so it is very helpful to improve the storage density and reduce the power consumption of the racetrack memory. The generation of magnetic domain wall is a very important step to study its application. Traditionally, a linear electrode perpendicular to the nanobelts is used to generate domain walls. Chapter 5th. In this paper, we propose a highly efficient electrode structure for injecting magnetic domains into vertically anisotropic nanoribbons with a current pulse of 5.35 脳 1011 A / m ~ 2 and a current pulse of 15 脳 10 ~ (11) A / m ~ (2). A magnetic domain was successfully generated in the Co/Ni multilayer in the pulse time of ns. The experimental and computational results show that the energy consumption of this method is only about 30% of that of the traditional method. The phenomenon of pinning and de-pinning of magnetic domain wall at cross cross structure is measured by anomalous Hall effect. The spin nanometer oscillator has a lot of excellent performance, but its output power is a bottleneck problem. Now there is a very good solution to the idea is to make an oscillator array, and then through the superposition of multiple oscillator signals to improve the output power. Chapter 6th. We study the oscillations of magnetic Skyrmion in a point-current-driven tunnel junction. Based on this principle, a novel spin nanoscilloscope oscillator based on magnetic Skyrmion is designed, which can output multiple signals simultaneously in a single device. Therefore, it is expected to increase the output power of the oscillator. The line width of the signal can be less than 1 MHz. The electrode can work at a current density of 108A / m ~ 2 and the minimum operating frequency can be close to 0 MHz, and the maximum working frequency can be up to the order of GHz.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：O342

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本文編號(hào)：1365101