本文選題：多層膜 + 反常能斯特效應(yīng)��； 參考：《中國科學(xué)院大學(xué)(中國科學(xué)院物理研究所)》2017年碩士論文

【摘要】：含有鐵磁層/非鐵磁層界面的多層膜體系一直以來作為自旋電子學(xué)的重要研究對象,可以提供多種特別的物理性質(zhì),如空間對稱性破缺、垂直磁各向異性,從而為電流翻轉(zhuǎn)磁矩、高密度存儲等多種具有巨大應(yīng)用價值的器件功能的實現(xiàn)提供了可靠的物理基礎(chǔ)。因此,對多層膜結(jié)構(gòu)的輸運特性的研究,特別是輸運性質(zhì)對多種物理場的響應(yīng)特征及其內(nèi)在機制的闡明,可為今后材料開發(fā)和器件應(yīng)用提供諸多借鑒。就此方面問題,本文主要闡述以下兩方面工作:(1)通過磁控濺射生長鉑/鈷多層膜,并加工為反常能斯特或反常霍爾效應(yīng)的測量結(jié)構(gòu)。通過電學(xué)輸運測量來表征體系中兩個效應(yīng)的特征量——反常霍爾角和反常能斯特系數(shù),討論二者隨著鐵磁/非磁界面數(shù)量增多的變化,以及二者之間的依賴關(guān)系。同時基于線性響應(yīng)理論,通過已有的唯象輸運模型來推導(dǎo)出二者間的關(guān)系式,并與實驗得到的結(jié)果作比較。綜合模型及實驗結(jié)果,得出二者存在著線性的正相關(guān)性,以及都隨著界面數(shù)量增多引起的體系自旋軌道耦合增強而增長的結(jié)論。(2)磁控濺射生長的鐵磁/氧化物勢壘/重金屬結(jié)構(gòu)經(jīng)過退火工藝誘導(dǎo)出面內(nèi)易磁化軸。經(jīng)微加工制備出具有一個頂電極和三個底電極的隧道結(jié)樣品。通過加載電流于結(jié)區(qū),實現(xiàn)自旋極化電流從鐵磁層注入重金屬層。注入的自旋可通過逆自旋霍爾效應(yīng)在兩個底電極之間探測到。另外,采用三端法加載交流電流測量結(jié)區(qū)電阻隨垂直膜面磁場變化引起的漢勒效應(yīng),得到結(jié)區(qū)電阻的磁場依賴特性,進行擬合得到重金屬鉑和鉭中的自旋弛豫時間。進一步結(jié)合電阻率的溫度依賴關(guān)系,推測出鉑中的自旋弛豫機制來自于E-Y機制。
[Abstract]:The multilayer system with ferromagnetic / non-ferromagnetic layer interface has been an important research object of spin electronics, which can provide a variety of special physical properties, such as space symmetry breaking, vertical magnetic anisotropy. This provides a reliable physical basis for the realization of the functions of many devices with great application value, such as current-flipping magnetic moment, high-density storage and so on. Therefore, the study of the transport characteristics of multilayer membrane structures, especially the response characteristics of transport properties to various physical fields and the elucidation of their internal mechanisms, can provide many references for the development of materials and the application of devices in the future. In this respect, this paper mainly describes the following two aspects of work: 1) growth of platinum / cobalt multilayers by magnetron sputtering and fabrication into anomalous Nernst or anomalous Hall effect measurement structures. The anomalous Hall angle and anomalous Nernst coefficient of the two effects in the system are characterized by electrical transport measurements. The variation of the two effects with the increase of the number of ferromagnetic / non-magnetic interfaces and their dependence are discussed. At the same time, based on the linear response theory, the relationship between the two is derived through the existing phenomenological transport model, and compared with the experimental results. By synthesizing the model and the experimental results, it is concluded that there is a positive linear correlation between the two models. The results show that the ferromagnetic / oxide barrier / heavy metal structure grown by magnetron sputtering is induced by annealing process to induce the internal magnetization axis. Tunnel junction samples with one top electrode and three bottom electrodes were fabricated by microfabrication. The spin-polarization current is injected into the heavy metal layer from the ferromagnetic layer by loading the current in the junction region. The injected spin can be detected by inverse spin Hall effect between two bottom electrodes. In addition, a three-terminal method is applied to measure the Hansel effect caused by the variation of the junction resistance with the magnetic field of the vertical film surface. The magnetic field dependence of the junction resistance is obtained, and the spin relaxation time in the heavy metal platinum and tantalum is obtained by fitting. Combining the temperature dependence of resistivity, it is inferred that the spin relaxation mechanism in platinum comes from the E-Y mechanism.
【學(xué)位授予單位】：中國科學(xué)院大學(xué)(中國科學(xué)院物理研究所)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB383.2
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本文編號：1982564