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This paper reports that the CoFe/IrMn bilayers are deposited by magnetron sputtering on the surfaces of thermallyoxidized Si substrates.It investigates the thermal relaxations of both non-irradiated and Ga + ion irradiated CoFe/IrMn bilayers by means of holding the bilayers in a negative saturation field.The results show that exchange bias field decreases with the increase of holding time period for both non-irradiated and Ga + ion irradiated CoFe/IrMn bilayers.Exchange bias field is also found to be smaller upon irradiation at higher ion dose.This reduction of exchange bias field is attributed to the change of energy barrier induced by ion-radiation. 相似文献
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《中国物理 B》2021,30(10):107501-107501
A multilayered spin valve film with a structure of Ta(5 nm)/Co_(75)Fe_(25)(5 nm)/Cu(2.5 nm)/Co_(75)Fe_(25)(5 nm)/Ir_(20)Mn_(80)(12 nm)/Ta(8 nm) is prepared by the high-vacuum direct current(DC) magnetron sputtering. The effect of temperature on the spin valve structure and the magnetic properties are studied by x-ray diffraction(XRD), atomic force microscopy(AFM), and vibrating sample magnetometry. The effect of temperature on the exchange bias field thermomagnetic properties of multilayered spin valve is studied by the residence time of samples in a reverse saturation field. The results show that as the temperature increases, the Ir Mn(111) texture weakens, surface/interface roughness increases, and the exchange bias field decreases. Below 200℃, the exchange bias field decreases with the residence time increasing, and at the beginning of the negative saturation field, the exchange bias field Hex decreases first quickly and then slowly gradually. When the temperature is greater than 200℃, the exchange bias field is unchanged with the residence time increasing. 相似文献
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采用磁控溅射的方法制备了一组以(Ni0.81Fe0.19)1-xCrx作为缓冲层的NiFe/PtMn双层膜样品,研究了NiFe/PtMn双层膜的形成过程和热稳定性.实验表明,Cr成分的不同会引起NiFe/PtMn双层膜中PtMn层晶粒尺寸的不同,使NiFe/PtMn双层膜的交换偏置场与PtMn层厚度之间呈现不同的变化关系.热稳定性实验表明,PtMn晶粒尺寸较大的样品,出现交换偏置现象所需要的临界厚度较小,热稳定性好,这与Mauri的理论模型一致.关键词：NiFe/PtMn双层膜交换偏置场热稳定性 相似文献
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将NiFe/PtMn双层膜生长在(Ni0.81Fe0.19)1-xCrx种子层材料上,通过改变种子层中Cr的原子含量,系统的研究了NiFe/PtMn双层膜中PtMn晶粒尺寸和织构对交换偏置的影响.对退火270℃,5h后的NiFe/PtMn双层膜磁性的研究表明,PtMn织构强弱对交换偏置场的影响不明显,而PtMn的晶粒尺寸是影响交换偏置场的主要因素,PtMn颗粒的相干长度在11.3nm左右时得到了较大的交换偏置场.关键词：NiFe/PtMn双层膜交换偏置场 相似文献
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研究了磁场诱导生长的BiFeO3/Ni18Fe19磁性双层膜中 的交换偏置及其热稳定性. 结果表明: BiFeO3/Ni18Fe19双层膜中的交换偏置场Hex未表现出明显的磁练习效应. 在负饱和磁场等待过程中, BiFeO3/Ni18Fe19双层膜磁滞回线的前支和后支曲 线都随着在负饱和磁场中等待时间tsat的增加向正场方向偏移. 交换偏置场Hex的大小随着等待时间tsat的增加而减小, 矫顽力Hc基本不变. 交换偏置场Hex的大小随测量温度Tm的升高变化不明显, 表现出良好的热稳定性; 但矫顽力Hc随Tm的升高而显著减小. 良好的热稳定性应该来源于铁电性和反铁磁性间的共同耦合作用.关键词：多铁性磁性薄膜交换偏置热稳定性 相似文献
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Yanan Tang Zhiyong Liu Weiguang Chen Zigang Shen Xiaolong Wang Xianqi Dai 《Molecular physics》2013,111(12):1898-1906
The structural stability and electronic property of metal Pt atom anchors on two typical substrates (including the pristine and defective bilayer graphene, PBG and DBG) are studied using the first-principles calculations. For the PBG sheets, the Pt atom at the bridge site of bottom layer has only one stable adsorption, which is more stable than other sites of the top layer. For the DBG sheets, the doped Pt below defective site has the larger adsorption energy than that of the upper one. Compared to the isolated graphene films, the Pt(111) substrate-supported graphene systems have effect on the adsorption energies of Pt adatom to some extent, but it does not affect the most preferable configurations. Moreover, the diffusion pathways and energy barriers of Pt adatom on PBG and DBG substrates are comparatively investigated. For the DBG sheets, the Pt dopant has smaller diffusion barrier on upper layer than that of the intercalation process through the defective site. Therefore, the Pt dopant prefers to diffuse on the top layer and then forms the metal impurity. This work provides valuable information on understanding the formation process and intercalation mechanism of metal adatom on graphene sheets. 相似文献
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利用磁控溅射法制备了Nd28Fe66B6/Fe50Co50 双层纳米复合磁性薄膜,研究了其结构和磁性.经873K退火处理15min 后,利用x射线衍射仪测定薄膜晶体结构,采用俄歇电子能谱仪估算薄膜厚度和超导量子干 涉仪测量其磁性.磁性测量表明,1)该系列薄膜具有垂直于膜面的磁各向异性.从起始磁化曲 线和小回线的形状特征可知,矫顽力机制主要是由畴壁钉扎控制.2)对于固定厚度（10nm） 层的硬磁相Nd-Fe-B和不同厚度（dFeCo=1—100nm）层软磁相FeCo双层纳米复合 膜,剩磁随软磁相FeCo 厚度的增加快速增加,而矫顽力则减少.当dFeCo=5nm 时 ,最大磁能积达到160×１０３A/m.磁滞回线的单一硬磁相特征说明,硬磁相Nd -Fe-B层和软磁相FeCo层之间的相互作用使两相很好地耦合在一起.剩磁和磁能积的提高是由 于两相磁性交换耦合所致.关键词：Nd-Fe-B/FeCo双层纳米复合膜交换耦合磁性增强 相似文献
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从能量和结构两个角度分析了BN四种相的转变过程,以及杂质和缺陷对立方氮化硼(c-BN)薄膜制备的影响.研究了从六角氮化硼(h-BN)到c-BN转变的一个可能的过程,即h-BN→菱形氮化硼(r-BN)→c-BN过程.对纯的h-BN到r-BN的转变需要克服一个很高的能量势垒,在实验室条件下很难能够提供能量来越过这个势垒.而从r-BN到c-BN的转变只需要克服一个很低的能量势垒.这个能量势垒要低于从h-BN到纤锌矿氮化硼(w-BN)转变所需要克服的能量势垒.c-BN薄膜的制备过程中,薄膜在高能粒子轰击下,会产生大量的缺陷,这些缺陷对立方相的形成起到了重要的作用,缺陷和杂质的存在大大降低了从h-BN到r-BN转变的能量势垒.根据这个理论模型,在两步法制备c-BN薄膜的基础上,调整实验参数,形成三步法制备高质量c-BN薄膜.主要研究了三步法中第一步的时间和衬底负偏压对c-BN薄膜制备的影响,找到合适的沉积时间和衬底负偏压分别为5min和-180V.采用三步法制备薄膜,可以重复得到高立方相体积分数(立方相体积分数超过80%)的BN薄膜,并且实验重复性达到70%以上.关键词：立方氮化硼能量势垒缺陷衬底偏压 相似文献
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The CoFe/Os/CoFe thin films were deposited on natural oxidized Si(1 0 0) substrates at room temperature by an ultra-high vacuum DC-magnetron sputtering system with a base pressure less than 1×10−8 Torr. The thickness of the ferromagnetic layers was 100 Å in all cases and a series of trilayers with Os spacer ranging from 3 to 20 Å was made. Effects of the Os layer thickness on the magnetoresistance (MR) and magnetic properties were investigated. The results showed that the magnetism switched from ferromagnetic (Os thickness=3, 5 Å) to antiferromagnetic (Os thickness=7–13 Å) and then ferromagnetic (Os thickness=20 Å) again. From the MR study, we see that the AMR ratio decreased from 4.64% to the minimum value 0.69% at 9 Å and then increased; GMR ratio increased from 0.01% to the maximum value 0.43% at 9 Å and then decreased. From the hysteresis loops, the results exhibited that coercivity increased from 16 Oe to the maximum value 92 Oe at 9 Å and then decreased, and squareness value decreased from 0.97 to the minimum value 0.17 at 9 Å and then increased. Dependence of saturation field on Os spacer-layer thickness for CoFe trilayers showed a maximum value 216 Oe at 9 Å. This suggests that the small GMR effect may be related to the small exchange coupling strength in CoFe/Os/CoFe thin films. 相似文献
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The structure dependence of exchange bias in ferromagnetic/antiferromagnetic （FM/AF） bilayers has been investigated in detail by extending Slonczewski＇s ＇proximity magnetism＇ idea. Here three important parameters are discussed for FM/AF bilayers, i.e. interracial bilinear exchange coupling J1, interracial biquadratic （spin-flop） exchange coupling J2 and antiferromagnetic layer thickness tAF. The results show that both the occurrence and the variety of the exchange bias strongly depend on the above parameters. More importantly, the small spin-flop exchange coupling may result in an exchange bias without the interracial bilinear exchange coupling. However, in general, the spin-flop exchange coupling cannot result in the exchange bias. The corresponding critical parameters in which the exchange bias will occur or approach saturation are also presented. 相似文献
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采用铁磁共振方法,研究了铁磁/反铁磁双层膜系统中,因交换耦合以及磁晶各向异性而产生的有效各向异性场.结果表明:被测系统有无交换偏置场以及其正负号性质等均能在共振谱中得到辨析.结果还显示:沿着不同结晶方向施加外磁场,共振场的行为与磁晶各向异性以及铁磁/反铁磁交换耦合作用而诱发的单向各向异性等密切相关.将共振频率的变化看成外磁场(包括其方向和大小)的函数,研究得到了单向各向异性,立方各向异性等对共振频率的影响,并同实验结果做了很好的比较.关键词：铁磁/反铁磁双层膜交换耦合铁磁共振单向各向异性 相似文献
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We have investigated the exchange bias and training effect in theferromagnetic/antiferromagnetic (FM/AF) heterostructures using aunified Monte Carlo dynamical approach. The magnetization of theuncompensated AF layer is still open after the first field cyclingis finished. Our simulated results show obvious shift of hysteresisloops (exchange bias) and cycling dependence of exchange bias(training effect) when the temperature is below 45~K. The exchangebias field decreases with decreasing cooling rate or increasingtemperature and the number of the field cycling. Essentially, thesetwo effects can be explained on the basis of the microscopicalcoexistence of both reversible and irreversible moment reversals ofthe AF domains. Our simulations are useful to understand the realmagnetization dynamics of such magnetic heterostructures. 相似文献
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铁磁/反铁磁双层膜中冷却场对交换偏置场的影响 总被引：1，自引：0，他引：1
用铁磁畴壁模型研究了非补偿界面铁磁/反铁磁双层膜中冷却场（包括大小及其方向）对交换偏置场hE的影响.结果表明：当冷却场的方向与反铁磁层磁易轴一致时,hE大小与冷却场大小无关.当冷却场的方向偏离磁易轴时,hE的大小随偏离角度的增大有缓慢的改变,但当冷却场的方向偏离到临界角度γc处,hE的大小发生突变,其γc的大小随冷却场的增大而增大.特别是当冷却场的偏离角度大于γc后,hE出现由负转正的现象,其转变点还与冷却场的大小有关.另外,hE与铁磁层原子层数NF的关系会发生由hE∝N-1F向hE∝N-λF的转变,其中λ>1.其发生转变的条件与NF、冷却场大小和方向密切相关.关键词：铁磁/反铁磁双层膜交换偏置冷却场 相似文献
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研究了在铁磁(NiFe)/反铁磁(FeMn)双层膜之间,交换偏置的形成过程和热稳定性,特别是NiFe/FeMn的交换偏置作用与FeMn层晶粒尺寸的关系.和以前作者不同的是,本文方法采用非磁性Ni-Fe-Cr合金作缓冲层材料,改变Cr的含量就可以获得不同晶粒尺寸的反铁磁FeMn层.实验表明,晶粒尺寸较小的FeMn产生较强的铁磁/反铁磁交换偏置场;但是,对于较大晶粒的FeMn层,出现交换偏置作用所要的临界厚度较小.这符合Mauri提出的理论模型.交换偏置场的热稳定性实验表明,具有较大晶粒尺寸的FeMn层给出较关键词：交换偏置热稳定性反铁磁晶粒尺寸 相似文献
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Jianjun Li 《Journal of magnetism and magnetic materials》2012,324(8):1512-1515
Choosing TbFe as the magnetostrictive layer and using soft ferromagnetic materials (FM=Fe, Py-permalloy, FeCo) as the inductive layer, we report the magnetization and magnetostriction of the S/FM(10 nm)/TbFe(10 nm) coupled bilayer (S-glass substrate). The magnetization of the coupled bilayer is attributed to the soft ferromagnetic layer and there is no contribution from the TbFe layer. Interfacial exchange interaction plays an important role in determining the magnetostriction of the coupled bilayer. The effect coming from the deposition Argon pressure on the magnetostriction of the coupled bilayer was also investigated. 相似文献
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X.F. Hu 《Applied Surface Science》2006,252(13):4625-4627
The synthetic antiferromagnets (SAF) have been used in spin-valve sensor in data storage industry [1]. We report a new hard/Ru/soft sandwich structure (SHBL) fabricated by pulsed lased deposition to replace current single layer structure for information recording application. SHBL consists of two magnetic layers separated by thin nonmagnetic layers, typically with Ru layers of 0.7-1.2 nm, through which antiferromagnetic coupling is induced. Varying the relative thickness of the magnetic layers, the spacer layers, and the type of magnetic materials can alter magnetic properties of CoCrPt/Ru/CoFe superlattice. The coercivity Hc and grain size of magnetic layer is also dependent on the laser fluence. High laser fluence results in both small grain size and high Hc. The observed phenomena are related to high quenching and deposition rates during PLD at high fluence, resulting in more pronounced phase segregation. 相似文献
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Ta,Ta/Cu缓冲层对NiFe/Fe Mn双层膜交换偏置场的影响 总被引：3，自引：1，他引：3
采用磁控溅射方法制备了分别以Ta和Ta/Cu作为缓冲层的一系列NiFe/FeMn双层膜.实验发现,以Ta为缓冲层的NiFe/FeMn双层膜的交换偏置场比以Ta/Cu为缓冲层的NiFe/FeMn双层膜的交换偏置场大.测量了这两种双层膜的织构、表面粗糙度和表面成分.结果表明,以Ta/Cu为缓冲层时,Cu在NiFe层的上表面偏聚是造成NiFe/FeMn双层膜交换偏置场降低的重要原因.关键词：NiFe/FeMn交换偏置场织构表面粗糙度 相似文献