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1.
Thickness-dependent magnetic properties in Pt/[Co/Ni]n multilayers with perpendicular magnetic anisotropy
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Chunjie Yan 《中国物理 B》2023,32(1):17503-017503
We systematically investigated the Ni and Co thickness-dependent perpendicular magnetic anisotropy (PMA) coefficient, magnetic domain structures, and magnetization dynamics of Pt(5 nm)/[Co($t_{\rm Co}$)/Ni($t_{\rm Ni}$)]$_{5}$/Pt(1 nm) multilayers by combining the four standard magnetic characterization techniques. The magnetic-related hysteresis loops obtained from the field-dependent magnetization $M$ and anomalous Hall resistivity (AHR) $\rho_{{xy}}$ showed that the two serial multilayers with $t_{\rm Co} = 0.2$ nm and 0.3 nm have the optimum PMA coefficient $K_{\rm U}$ as well as the highest coercivity $H_{\rm C}$ at the Ni thickness $t_{\rm Ni}= 0.6 $ nm. Additionally, the magnetic domain structures obtained by magneto-optic Kerr effect (MOKE) microscopy also significantly depend on the thickness and $K_{\rm U}$ of the films. Furthermore, the thickness-dependent linewidth of ferromagnetic resonance is inversely proportional to $K_{\rm U}$ and $H_{\rm C}$, indicating that inhomogeneous magnetic properties dominate the linewidth. However, the intrinsic Gilbert damping constant determined by a linear fitting of the frequency-dependent linewidth does not depend on the Ni thickness and $K_{\rm U}$. Our results could help promote the PMA [Co/Ni] multilayer applications in various spintronic and spin-orbitronic devices. 相似文献
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J.F. Feng K. RodeK. Ackland P.S. StamenovM. Venkatesan J.M.D. Coey 《Journal of magnetism and magnetic materials》2012
Perpendicular magnetic anisotropy (PMA) has been investigated in ultrathin (CoFe [0.2] nm/Pt [0.2] nm)n multilayers. The Pt layers show an fcc crystal structure with a preferred [111] orientation. The multilayers with n=3, 4 show PMA in the as-grown state, which can be enhanced by thermal annealing. However, no PMA is observed in the as-grown state with higher repetitions (n>&=5), although it is observed after thermal annealing. For 1=&<n=&<8, the anisotropy energy is around 105 J/m3 for all (CoFe [0.2]/Pt [0.2])n stacks. The perpendicular anisotropy is related to layer thickness and interface roughness. 相似文献
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In this work, the variation of the magnetic moments of the Ni/Pt multilayers are studied using the linearized augmented plane waves (LAPW) method in the framework of the density functional theory (DFT) implemented in the version of WIEN2K program. The systems have been modeled by seven layers slab separated in z direction by a vacuum region of four substrate layers. We present the results of the dependence of the magnetic properties with respect to the thickness variation of the different multilayers. The modeling of these systems finds an important empirical support. Experiment and theory show the same trends for the magnetic moments: hybridization effects between Ni and Pt are mostly localized at the interface. 相似文献
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F. Rose O. Schulte P. Schaaf W. Lohstroh W. Felsch 《Applied Physics A: Materials Science & Processing》1996,63(2):183-190
The structural and magnetic properties of La/Fe multilayers were investigated by X-ray diffraction, RHEED, magnetometry and57Fe Mössbauer spectroscopy. Comparison is made with previous results obtained for Ce/Fe multilayers. Remarkably sharp interfaces are found, with roughness between 2 and 2.5 Å. The magnetic interface in the Fe sublayers resulting from the distribution of magnetic hyperfine fields distinctly exceeds the extension of the structural interface and points to a magnetic proximity effect. This is discussed in relation to a strong 3d-5d hybridization recently found in measurements of magnetic circular X-ray dichroism. Both the structural and magnetic La/Fe interface is less extended than the interface in Ce/Fe multilayers. Below a thickness of about 25 Å, the individual Fe layers grow in an amorphous structure on the La layers. In this case, Curie temperatures are below 200 K and the Fe-layer saturation magnetization is reduced up to 50%, and there is evidence of a non-collinear spin structure. It is argued that this mainly reflects the properties of pure amorphous Fe. 相似文献
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Co/Ti multilayers with wedge-shaped Co or Ti sublayers were prepared using UHV (5×10−10 mbar) DC/RF magnetron sputtering. The planar growth of the Co and Ti layers was confirmed in situ by X-ray photoelectron spectroscopy. Cobalt sublayers grow on sufficiently thick titanium sublayers in the soft magnetic nanocrystalline phase up to a critical thickness dcrit3.0 nm. For a thickness greater than dcrit, the Co sublayers undergo a structural transition to the polycrystalline phase with much higher coercivity. Furthermore, for the Co/Ti multilayers with nanocrystalline Co sublayers with dCo=2.7 nm we have observed a significant drop of the coercivity — typically from Hc3.5 kA/m to Hc0.2 kA/m — for Ti thickness dTi0.35 nm. The above effect could be explained by the existence of a minimum Ti sublayer thickness (dmin0.35 nm), which is required for the nanocrystalline growth of Co, and/or the formation of quasi-continuous non-magnetic layers for dTidmin giving rise to a decrease of the exchange energy between Co sublayers. Magnetic domains and walls studies revealed the structural transitions of the Co sublayers. 相似文献
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O. Donzelli G. Fratucello F. Ronconi J. Tejada Z. Rachid X. X. Zhang 《Hyperfine Interactions》1992,68(1-4):303-306
The magnetic properties of (111) Cu/Fe multilayers grown on Cu underlayers of several thickness (2000-500-50 Å) on cleaved mica have been investigated by Mössbauer spectroscopy and SQUID magnetometry. The analysis of experimental results suggests that 2.5 monolayers of ψ-Fe interfaced with Cu evolves partially from paramagnetic to ferromagnetic states as the Cu underlayer thickness is reduced to 50 Å and partially from weak to strong antiferromagnetism. 相似文献
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Yukai An Lingshen Duan Tao LiuZhonghuan Wu Jiwen Liu 《Applied Surface Science》2011,257(17):7427-7431
[Co(30 Å)/Pt(x Å)]20 multilayers with the Pt layer thicknesses varying from 5 Å to 20 Å were characterized structurally by high angle X-ray diffraction, X-ray reflectivity, X-ray absorption spectroscopy and magnetically by X-ray magnetic circular dichroism. It is found that the structure and magnetic properties of Pt have a strong correlation with the Pt layer thickness. The 20 Å thickness Pt layer is not almost influenced by the adjacent Co layer and the nearest neighbors are dominated by Pt-Pt shells. With decreasing Pt layer thickness, the nearest neighbors are gradually dominated by Pt-Co shells and the Pt-Co intermixing regions also remarkable increase at the interfaces, especially for the 5 Å thickness Pt layer. The orbital and spin magnetic moments as well as the ratio morb/mspin all decrease systematically with increasing Pt layer thickness, indicating that the interface atoms are polarized by direct Pt-Co hybridization, but that the adjacent layers are polarized by Pt-Pt interactions. 相似文献
9.
Yousong Gu Dayong ZhangXiaoyuan Zhan Zhen JiYue Zhang 《Journal of magnetism and magnetic materials》2006
Series of [FePt(4min)/Fe(tFe)]10 multilayers have been prepared by RF magnetron sputtering and post-annealing in order to optimize their magnetic properties by structural designs. The structure, surface morphology, composition and magnetic properties of the deposited films have been characterized by X-ray diffractometer (XRD), Rutherford backscattering (RBS), scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDX) and vibrating sample magnetometer (VSM). It is found that after annealing at temperatures above 500 °C, FePt phase undergoes a phase transition from disordered FCC to ordered FCT structure, and becomes a hard magnetic phase. X-ray diffraction studies on the series of [FePt/Fe]n multilayer with varying Fe layer thickness annealed at 500 and 600 °C show that lattice constants change with Fe layer thickness and annealing temperature. Both lattice constants a and c are smaller than those of standard ones, and lattice constant a decreases as Fe layer deposition time increases. Only a slight increase in grain size was observed as Fe layer decreased in samples annealed at 500 °C. However, the increase in grain size is large in samples annealed at 600 °C. The coercivities of [FePt/Fe]n multilayers decrease with Fe layer deposition time, and the energy product (BH)max reaches a maximum in the samples with Fe layer deposition time of 3 min. Comparison of magnetic properties with structure showed an almost linear relationship between the lattice constant a and the coercivities of the FePt phase. 相似文献
10.
Snehal Jani Varkey Sebastian N. Lakshmi V. R. Reddy K. Venugopalan Ajay Gupta 《Hyperfine Interactions》2008,185(1-3):23-28
Fe/Al multilayer thin films prepared by ion beam sputtering, with an overall atomic concentration ratio of Fe/Al = 1:2 have been studied by x-ray diffraction spectroscopy (XRD), X-ray reflectivity (XRR) and D.C. Magnetization. These studies show the formation of Fe–Al intermetallic layers. Two magnetic regions and transition temperatures of 473 and 533 K are evident from magnetization studies. Conversion Electron Mössbauer Spectroscopy (CEMS) shows formation of off-stoichiometric Fe3Al like phase and phases consisting of pure Fe and Fe-rich extended Fe–Al solutions. 相似文献
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采用磁控溅射方法制备了以Pt为缓冲层和保护层的具有垂直各向异性(Pt/Co)n/FeMn多层膜.研究结果表明,多层膜的垂直交换偏置场Hex和反铁磁层厚度的关系与其具有平面各向异性的交换偏置场随反铁磁层厚度变化趋势相近.随着铁磁层调制周期数的增加,垂直交换偏置场Hex相应减小,并且与铁磁层的调制周期数近似成反比关系.(Pt/Co)3/FeMn的垂直交换偏置场Hex已经达到22.3kA/m.为了进一步提高Hex,在Co/FeMn的界面插入Pt层,当Pt层厚度为0.4nm时,Hex达到最大值39.8kA/m. 相似文献
15.
《Journal of magnetism and magnetic materials》1999,192(3):423-430
Polycrystalline (Fe/Pd)n multilayers are grown onto sapphire substrates at room temperature in a UHV system. The number of periods n=40 and the thickness of Pd layers of tPd=4 nm are kept constant, whereas the thickness of the Fe layers is varied from 1.5 to 5 nm. Structural properties are studied by in situ reflection high energy diffraction (RHEED), scanning tunnelling microscopy (STM) and ex situ by X-ray diffraction at small angles and large angles. Analyzing the experimental data using the program SUPREX we obtain interplanar distances of dFe=2.03±0.01 Å for an Fe layer thickness larger than about 2.5 nm as expected for (1 1 0) planes of BCC Fe. For Fe layers with thicknesses less than about 2.5 nm the interplanar distance is dFe=2.1±0.01 Å, which is close to the distance between (1 1 1) planes of FCC Fe with a lattice parameter of a=3.64 Å. Magnetic susceptibility measurements at temperatures between 1.5 and 300 K for (Fe/Pd)n multilayers with FCC Fe yield a magnetic moment per Fe atom of μ=2.7±0.1 μB, which is about 20% larger compared to μ=2.2 μB for BCC Fe. We show that the occurrence of the large magnetic moment originates from FCC Fe being in the high spin (HS) state rather than from polarization effects of Pd at Fe/Pd interfaces. 相似文献
16.
Fe/Al thin film multilayers, differing in the thickness of Fe films (30÷10 Å, were electron-beam evaporated in ultra-high vacuum. Interdiffusion and reaction phenomena occurring during deposition at interfaces were studied by means of conversion electron Mössbauer spectroscopy and Auger electron spectroscopy depth-profiling. Magnetic behavior was investigated by alternating force gradient magnetometry. The formation of Fe–Al solid solution and intermetallic compound is observed. Multilayers are ferromagnetic with magnetization in the film plane for iron film thickness ?15 Å, while exhibiting a superparamagnetic behavior at 10 Å. 相似文献
17.
F. Klose J. Thiele A. Schurian O. Schulte M. Steins O. Bremert W. Felsch 《Zeitschrift für Physik B Condensed Matter》1993,90(1):79-82
Multilayers of Ce and Fe show a low Curie temperature and saturation magnetization below a critical thickness of the individual Fe layers where amorphous growth occurs. We have studied on a series of such multilayers with different modulation lengths prepared by ion-beam sputtering the impact of hydrogen absorption on their magnetic properties. Hydrogenation was performed during film growth either reactively by introducing hydrogen gas into the UHV chamber or by irradiation with a beam of low-energy hydrogen ions. Hydrogen is absorbed only in the Ce layers, with a concentration near CeH2. For suitable modulation lengths, the Curie temperature and saturation magnetization are considerably enhanced with respect to the non-hydrided multilayers. This is correlated with the changes in structure and the quality of the interfaces induced by hydrogenation: the irradiation process itself reduces the critical thickness for amorphous growth of Fe, and the chemical interaction of hydrogen causes a considerable sharpening of the interfaces. 相似文献
18.
X.W. Li C. Song R.L. Zong F. Zeng J. Yang S.P. Wen F. Pan 《Applied Physics A: Materials Science & Processing》2008,90(2):305-310
This study examines the microstructures and magnetic properties of (CoZr10 nm/M10 nm)20 (M=Cu, Ag, Al, Cr) multilayers prepared by direct current magnetron sputtering. The structural characterizations show that
CoZr layers have an amorphous structure, but a slight dissimilarity of local structure exists among the amorphous phases,
which is most likely affected by the different polycrystalline M layers. Consequently, the soft magnetic properties of (CoZr10 nm/M10 nm)20 multilayers are strongly dependent on the non-magnetic M layers. On the other hand, an in-plane uniaxial magnetic anisotropy
is observed for all multilayers, which can be attributed to the tensile stress induced by sample rotation during film deposition.
A combination of Cu serving as non-magnetic layers and tensile stress is the key to enhancing the soft magnetic properties
of CoZr-based films. The mechanisms responsible for the dependence of the magnetic properties on non-magnetic M layers and
tensile stress are discussed.
PACS 68.55.-a; 75.50.Kj; 75.70.-i; 75.30.Gw; 75.60.Ej 相似文献
19.
R. Hübler S. R. Teixeira W. H. Schreiner I. J. R. Baumvol 《Applied Physics A: Materials Science & Processing》1992,54(5):437-441
The structure, composition, and magnetic characteristics of thin films multilayers of iron-iron nitride with high magnetic moment and very low coercive field are investigated. The present study together with previous ones that described in detail the magnetic properties lead to the establishment of certain requirements to obtain iron-iron nitride multilayers with outstanding magnetic characteristics.Supported in part by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Brazil) 相似文献
20.
This paper reports on the change in the magnetic and the structural properties of Pt/Cr/Co multilayers due to 1 MeV N+-ion irradiation at room temperature. We observe irradiation induced formation of the CoCrPt ternary alloy phase at a fluence of 1×1016 ions cm?2. Phase formation is accompanied by an enhancement in the coercivity. The enhancement in the coercivity is attributed to inhomogeneous alloying and possible mixing-induced strain. These findings are explained in the light of ion beam induced recoil mixing and ionization events. 相似文献