本文選題：垂直磁各向異性 + 磁晶各向異性能　； 參考：《北京科技大學(xué)》2015年博士論文

【摘要】：傳統(tǒng)磁存儲(chǔ)要實(shí)現(xiàn)超高的存儲(chǔ)密度就需要進(jìn)一步減小磁盤(pán)中磁性顆粒的尺寸。由于磁性顆粒體積減小到一定程度就會(huì)出現(xiàn)超順磁效應(yīng),我們需要使用具有高磁晶各向異性能的磁性材料來(lái)確保小尺寸下磁性顆粒的熱穩(wěn)定性。Co基磁性材料一直被當(dāng)做制備超高密度存儲(chǔ)介質(zhì)的有力候選材料。根據(jù)對(duì)密排六方Co基磁性材料各向異性能的系統(tǒng)研究,許多Co基磁性材料(如Sm-Co, Co-W, Co-Mo等)的磁晶各向異性能都大于現(xiàn)在硬盤(pán)中所使用的磁性材料Co-Cr-Pt。本研究在若干不同的材料體系中成功制備了Co基垂直各向異性磁性薄膜,并對(duì)其機(jī)理、形貌、微觀織構(gòu)、磁學(xué)性能等方面的性質(zhì)進(jìn)行了深入系統(tǒng)的研究,還參與了h-BN隔離層磁隧道結(jié)制備中薄膜制備工藝優(yōu)化方面的研究,主要結(jié)論如下： (1)在Ru(0002)織構(gòu)的緩沖層上成功外延生長(zhǎng)出了具有優(yōu)異垂直磁各向異性的SmCo5-xCux薄膜。同時(shí),深入研究了Cu摻雜對(duì)SmCo5-xCux薄膜的磁性和微觀晶體結(jié)構(gòu)的影響。隨著Cu含量的增加,SmCo5-xCux薄膜的居里溫度(Tc)大幅下降。SmCo5-xCux具有超高的垂直各向異性能和可以調(diào)節(jié)的居里溫度,這意味著SmCo5-xCux在常溫下具有良好的熱穩(wěn)定性,而在高溫下易于寫(xiě)入,這種優(yōu)異的特性使SmCo5-xCux極有望成為一種新型的超高密度熱輔助磁記錄(HAMR)介質(zhì)材料。 (2)根據(jù)米德馬(Miedema)半經(jīng)典模型計(jì)算出Co-W二元合金的晶態(tài)與非晶體的熱力學(xué)形成焓。熱力學(xué)計(jì)算結(jié)果表明在W的原子百分比低于17.5%的時(shí)候Co-W薄膜更傾向于形成密排六方相�；跓崃W(xué)計(jì)算結(jié)果,我們利用磁控濺射系統(tǒng)制備了一系列不同W含量的Co-W薄膜。經(jīng)過(guò)真空熱退火,我們成功地增強(qiáng)了Co-W薄膜的垂直矯頑力,同時(shí)Co-W薄膜的磁晶各向異性能常數(shù)Ku達(dá)到了2.1×106erg/cm3。在本研究中Co-W薄膜的垂直矯頑力達(dá)到了1147Oe,這大大提高了Co-W材料成為下一代超高密度磁存儲(chǔ)材料的可能性。 (3)成功在Ta緩沖層上制備出垂直各向異性的TbFeCo磁性薄膜,并深入研究了底層Ta的厚度對(duì)TbFeCo磁性層磁性的影響。我們發(fā)現(xiàn)由于磁性釘扎位數(shù)量的增長(zhǎng),TbFeCo層的垂直矯頑力會(huì)隨著Ta層厚度的增加而明顯增加。增加Ta層的厚度可以避免TbFeCo層中Tb原子被氧化,從而降低TbFeCo層的飽和磁化強(qiáng)度。當(dāng)Ta層厚度達(dá)到4nm以后,TbFeCo層會(huì)有接近于1的剩磁比。 (4)研究利用六方氮化硼(h-BN)作為隔離層的磁隧道結(jié)的制備工藝、薄膜形貌與織構(gòu)優(yōu)化。最終利用快速熱退火的方法制備出具有hcp Co/h-BN/hcp Co三明治結(jié)構(gòu)的磁性薄膜。為以后的微加工制備h-BN隔離層磁隧道結(jié)打下了良好的基礎(chǔ)。
[Abstract]:Traditional magnetic storage needs to reduce the size of magnetic particles in order to achieve high storage density. As the volume of magnetic particles decreases to a certain extent, there will be superparamagnetic effect. We need to use magnetic materials with high magnetocrystalline anisotropic energy to ensure the thermal stability of magnetic particles at small size. Co-based magnetic materials have been used as a powerful candidate for preparing ultra-high density storage media. Based on the systematic study of anisotropic energy of compact hexagonal Co based magnetic materials, many Co based magnetic materials (such as Sm-Co, Co-W, Co-Mo, etc.) have higher magnetocrystalline anisotropy energy than the Co-Cr-Pts used in the present hard disk. In this paper, the perpendicular anisotropic magnetic thin films on Co substrates have been successfully prepared in several different material systems. The mechanism, morphology, microtexture and magnetic properties of the films have been studied systematically and thoroughly. It also participated in the study on the optimization of thin film preparation in the preparation of h-BN isolation layer magnetic tunnel junction. The main conclusions are as follows: 1) SmCo5-xCux thin films with excellent vertical magnetic anisotropy have been successfully grown on the buffer layer of Ruz0002) texture. At the same time, the effect of Cu doping on the magnetic properties and microstructure of SmCo5-xCux thin films was investigated. With the increase of Cu content, the Curie temperature of SmCo5-xCux thin film decreases significantly. SmCo5-xCux has high vertical anisotropy energy and adjustable Curie temperature, which means that SmCo5-xCux has good thermal stability at room temperature, but easy to write at high temperature. With this excellent property, SmCo5-xCux is expected to be a new type of ultrahigh density thermally assisted magnetic recording (Ham) dielectric material. (2) the enthalpy of formation between crystalline and amorphous of Co-W binary alloy is calculated based on the semiclassical model of Miedemia). The thermodynamic results show that Co-W films tend to form dense hexagonal phase when the atomic percentage of W is less than 17.5%. Based on the thermodynamic results, a series of Co-W films with different W content were prepared by magnetron sputtering system. After vacuum thermal annealing, the vertical coercivity of Co-W thin films has been successfully enhanced, and the magnetocrystalline anisotropy energy constant Ku of Co-W thin films has reached 2.1 脳 10 6 erg / cm 3. In this study, the vertical coercivity of Co-W thin films reaches 1147Oe, which greatly enhances the possibility of Co-W materials becoming the next generation ultra-high density magnetic storage materials. TbFeCo magnetic thin films with vertical anisotropy were successfully prepared on Ta buffer layer, and the effect of the thickness of Ta on the magnetic properties of TbFeCo magnetic layer was studied. It is found that the vertical coercivity of TbFeCo layer increases with the increase of Ta layer thickness due to the increase of the number of magnetic pinning positions. Increasing the thickness of Ta layer can avoid the oxidation of TB atoms in TbFeCo layer, thus reducing the saturation magnetization of TbFeCo layer. When the thickness of Ta layer reaches 4nm, the TbFeCo layer will have a remanent magnetic ratio close to 1. (4) the preparation process of magnetic tunnel junctions using hexagonal boron nitride h-BN as isolation layer and the optimization of film morphology and texture were studied. Finally, magnetic films with hcp Co/h-BN/hcp Co sandwich structure were prepared by rapid thermal annealing. It lays a good foundation for the preparation of h-BN isolation layer magnetic tunnel junctions by micromachining.
【學(xué)位授予單位】：北京科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB383.2

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本文編號(hào)：1959177