共查询到20条相似文献,搜索用时 894 毫秒
1.
Yong-Goo Yoo Seong-Gi Min Ho-Jun Ryu Nam-Seok Park Seong-Cho Yu 《Journal of magnetism and magnetic materials》2006
Exchange biased IrMn/NiFe/IrMn thin films were studied as a function of NiFe thickness. In plane angular dependence of a resonance field distribution which is measured by FMR was analyzed as a combined effect of an unidirectional anisotropy and an uniaxial anisotropy. The unidirectional anisotropic field and the uniaxial anisotropic field were linearly varied with NiFe thickness while the films with a thicker NiFe layer do not follow the linear variation. Resonance field and linewidth variations were also analysed with NiFe thickness. 相似文献
2.
The effect of the antiferromagnetic IrMn thickness upon the magnetic properties of CoFe/Pt/CoFe/[IrMn(tIrMn)] multilayers is studied. An oscillatory interlayer coupling (IEC) has been shown in pinned CoFe/Pt(tPt)/CoFe/IrMn multilayers with perpendicular anisotropy. The period of oscillation corresponds to about 2 monolayers of Pt. The oscillatory behavior of IEC depends on the nonmagnetic metallic Pt thickness and is thought to be related to the antiferromagnetic ordering induced by the IrMn layer. From the extraordinary Hall voltage amplitude (EHA) curves as function of IrMn thickness, we report that the oscillation dependence of IEC for the [CoFe/Pt/CoFe] multilayer system induced by IrMn with spacer-layer thickness is a important features of perpendicular exchange biased system. 相似文献
3.
Martí X Park BG Wunderlich J Reichlová H Kurosaki Y Yamada M Yamamoto H Nishide A Hayakawa J Takahashi H Jungwirth T 《Physical review letters》2012,108(1):017201
We employ antiferromagnetic tunneling anisotropic magnetoresistance to study the behavior of antiferromagnetically ordered moments in IrMn exchange coupled to NiFe. Experiments performed by common laboratory tools for magnetization and electrical transport measurements allow us to directly link the broadening of the NiFe hysteresis loop and its shift (exchange bias) to the rotation and pinning of antiferromagnetic moments in IrMn. At higher temperatures, the broadened loops show zero shift, which correlates with the observation of fully rotating antiferromagnetic moments inside the IrMn film. The onset of exchange bias at lower temperatures is linked to a partial rotation between distinct metastable states and pinning of the IrMn antiferromagnetic moments in these states. The observation complements common pictures of exchange bias and reveals an electrically measurable memory effect in an antiferromagnet. 相似文献
4.
《Journal of magnetism and magnetic materials》2001,225(3):403-410
Approximate analytic solutions for the energy of an antiferromagnetic (AF) grain, which experiences an external exchange torque from a ferromagnetic grain have been obtained for a wide range of AF thickness. The accuracy of the analytic expression is within 2.0% of the exact solution, which do not have a closed analytical form. The model predicts that there are two critical AF grain thickness for each particular exchange energy strength. Below the first critical thickness, the induced anisotropy energy is well approximated by an uniaxial anisotropy term. Above the second critical thickness the induced anisotropy is unidirectional. In the intermediate range the induced anisotropy can not be expressed simply as uniaxial or unidirectional. The exchange bias and coercivity in NiFe/IrMn films have been studied as a function of the IrMn thickness, and the results are consistent with the proposed theory. 相似文献
5.
Xiao-Li Tang Huai-Wu ZhangHua Su Zhi-Yong ZhongYu-Lan Jing 《Journal of magnetism and magnetic materials》2007
A conventional Ta/NiFe/Cu/NiFe/FeMn/Ta spin valve multilayer was prepared to investigate the exchange bias variations of the pinned NiFe layer. An exchange bias field of 560 Oe has been found in a valve multilayer with ultra-thin pinned NiFe layers (1 nm), in which a large constant magnetic field of 700 Oe was applied during film deposition procession. The observed results are attributed to the large applied magnetic field, which produced more net spins of the antiferromagnet at the interface. These interfacial uncompensated spins provide the net spin moments required for exchange coupling and bias. 相似文献
6.
Morgunov R. B. Talantsev A. D. Bakhmet’ev M. V. Granovskii N. V. 《Physics of the Solid State》2020,62(6):1033-1038
Physics of the Solid State - In the NiFe/Ta/IrMn structures, the contributions of two types of exchange interactions at the NiFe/IrMn interface, partially separated by sections of the nonmagnetic... 相似文献
7.
X.L. Tang H. Wu Zhang H. Su Y.L. Jing Z. Yong Zhong 《Journal of magnetism and magnetic materials》2009,321(18):2855-2858
A conventional Ta/NiFe/Cu/NiFe/FeMn spin valve was prepared to investigate the exchange bias properties with the variations of deposition field. By enhancing the deposition magnetic fields from 50 to 650 Oe, increase of exchange bias fields at a given thickness of the pinned NiFe layer has been found in the spin valves. In this paper, we show that this increase is due to the change of magnetic moment distribution at the ferromagnetic and antiferromagnetic interface by comparison of measured results with the interfacial uncompensated model. Therefore, by enhancing deposition magnetic fields, a large exchange-coupling field can be achieved in relatively thicker magnetic films for application. 相似文献
8.
In this paper, the magnetization reversal of the ferromagnetic
layers in the IrMn/CoFe/AlOx/CoFe magnetic tunnel junction has
been investigated using bulk magnetometry. The films exhibit very
complex magnetization processes and reversal mechanism. Thermal
activation phenomena such as the training effect, the asymmetry of
reversal, the loop broadening and the decrease of exchange field
while holding the film at negative saturation have been observed on
the hysteresis loops of the pinned ferromagnetic layer while not on
those of the free ferromagnetic layer. The thermal activation
phenomena observed can be explained by the model of two energy
barrier distributions with different time constants. 相似文献
9.
Yong-Goo Yoo Seong-Cho Yu P.D. Kim B.A. Belyaev A.M. Mahlaev D.L. Khalyapin 《Journal of magnetism and magnetic materials》2006
The exchange coupling strength of NiFe/Cu/IrMn trilayer films was examined with both a new magneto optical Kerr effect (MOKE) method developed for the exchange coupling field determination and ferromagnetic resonance (FMR) measurements. We found that the value for exchange coupling field obtained by the MOKE technique coincided with FMR result with high accuracy. Other peculiarities of FMR measurements due to interlayer exchange coupling such as angular dependence of resonance field on Cu spacer thickness are also shown in the article. 相似文献
10.
D. Spenato J. Ben Youssef H. Le Gall 《Journal of magnetism and magnetic materials》2002,240(1-3):254-256
The spin dynamics of the ferromagnetic pinned layer of ferro-antiferromagnetic coupled NiFe/MnNi bilayers is investigated in a broad frequency range (30 MHz–6 GHz). A phenomenological model based on the Landau-Lifshitz equation for the complex permeability of the F/AF bilayer is proposed. The experimental results are compared to theoretical predictions. 相似文献
11.
Sang-Il Kim Min-Su SeoJung-Hye Seo Hyung Joong YunJouhahn Lee Yeon Suk Choi Seung-young Park 《Current Applied Physics》2014,14(12):1743-1747
The Inverse Spin Hall Effect (ISHE) voltage induced by spin-pumping was measured in Pt/[nonoxidized or oxidized NiFe] samples. The spectrum shape of the DC voltage signal was well-reproduced by simple Lorentzian functions, which were consistent with the prediction of ISHE in Pt/nonoxidized NiFe sample. On the other hand, the voltage signal from the Pt/oxidized NiFe was significantly decreased in accordance with abnormal ferromagnetic resonance (FMR) behavior. The origin of the ISHE voltage degradation was investigated by the FMR spectrum and X-ray photoelectron spectroscopy (XPS) analyses. The spin-pumping was suppressed by the oxidation of NiFe layer and deficient Pt/NiFe interface. The well-defined ferromagnet and clear interface with a normal spin mixing conductance were experimentally demonstrated to be reasonable spin-pumping. 相似文献
12.
L.C.C.M. Nagamine G.M.B. Castro J. Geshev M.N. Baibich E.B. Saitovitch J.E. Schmidt 《Journal of magnetism and magnetic materials》2008,320(14):e16-e18
The influence of the Cu layer thickness on the magnetic and magnetotransport properties has been investigated in Ta/NiFe/Cu/NiFe/FeMn spin valves. The magnetization and magnetoresistance measurements were carried out for magnetic field applied along the easy-axis direction. A phenomenological model, which assumes formation of a planar domain wall at the anti-ferromagnetic side of the interfaces as well as bilinear coupling between the ferromagnetic layers, was used to derive the anisotropy characteristics and orientation of each NiFe layer magnetization. The anisotropy and spin valve magnetoresistance were simulated numerically and compared with the experiment. It was found that the anisotropy magnetoresistance is negligible and that there is a poor agreement for the spin-valve one, which was attributed to the model (valid for ferromagnetic layers in single-domain state only) used for its calculation. It was found that the increase of the Cu layer thickness provokes a decrease of the interdiffusion between the NiFe and FeMn layers, and, as consequence, changes of the uniaxial anisotropy of the pinned NiFe layer, of the exchange interaction between the pinned NiFe layer and the FeMn ones, as well as of the exchange-bias field of the pinned NiFe layer. 相似文献
13.
Broad-Band FMR Linewidth of Co_2MnSi Thin Films with Low Damping Factor:The Role of Two-Magnon Scattering
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《中国物理快报》2016,(4)
The low Gilbert damping factor,which is usually measured by ferromagnetic resonance,is crucial in spintronic applications.Two-magnon scattering occurs when the orthogonality of the ferromagnetic resonance mode and other degenerate spin wave modes was broken by magnetic anisotropy,voids,second phase,surface defects,etc.,which is important in analysis of ferromagnetic resonance linewidth.Direct fitting to linewidth with Gilbert damping is advisable only when the measured linewidth is a linear function of measuring frequency in a broad band measurement.We observe the nonlinear ferromagnetic resonance linewidth of Co_2MnSi thin films with respect to measuring frequency in broad band measurement.Experimental data could be well fitted with the model including two-magnon scattering with no fixed parameters.The fitting results show that two-magnon scattering results in the nonlinear linewidth behavior,and the Gilbert damping factor is much smaller than reported ones,indicating that our Co_2 MnSi films are more suitable for the applications of spin transfer torque. 相似文献
14.
J. Moritz P. Bacher S. Auffret B. Dieny 《Journal of magnetism and magnetic materials》2011,323(18-19):2391-2397
The interlayer exchange coupling between Co/Pt perpendicular-to-plane magnetized layers across a thin IrMn spacer layer was experimentally studied. In contrast to earlier studies on interlayer coupling through antiferromagnetic NiO, which revealed an oscillatory coupling behavior as a function of NiO thickness, a ferromagnetic coupling was observed here in the range of IrMn thickness between 0.6 and 1.5 nm and antiferromagnetic between 1.5 and 2.5 nm. The antiferromagnetic coupling is attributed to an orange peel magnetostatic mechanism whereas the ferromagnetic coupling is attributed to an out-of-plane polarization of the antiferromagnetic IrMn layer induced by the interfacial exchange interaction with the adjacent out-of-plane ferromagnetic layers. Measurements of hysteresis loops versus temperature show that the coupling vanishes at 510 K for tIrMn=1 nm. This critical temperature is far below the Néel temperature of bulk IrMn, but above the blocking temperature of IrMn/Co bilayers at such thickness. Using a one-dimensional model describing a partial domain wall in the antiferromagnet, we explain the coupling in terms of an out-of-plane tilt of the Mn moments at the IrMn/(Co/Pt) interfaces yielding a weak net polarization of the IrMn. Finally, the non-oscillatory decay of the coupling was attributed to the compensated spin structure of the IrMn in the parallel to the interfaces. 相似文献
15.
The temperature dependencies of the ferromagnetic
resonance (FMR) linewidth and the resonance field-shift have been
investigated for NiO/NiFe exchange-biased bilayers from 78 K to 450 K. A broad maximum in the linewidth of 500 Oe, solely due to the
exchange-bias, is observed at ≈150 K when the magnetic
field is applied along the film plane. When the magnetic field is
applied perpendicular to the film plane, the maximum in the
linewidth is less pronounced and amounts to 100 Oe at the same
temperature. Such a behavior of the FMR linewidth is accompanied
with a monotonic increase in the negative resonance field-shift
with decreasing temperature. Our results are compared with the
previous experimental FMR and Brillouin light scattering data for
various ferromagnetic/antiferromagnetic (FM/AF) structures, and
suggest that spin dynamics (spin-wave damping and anomalous
resonance field-shift) in the FM/AF structures can be described in
a consistent way by a single mechanism of the so-called
slow-relaxation. 相似文献
16.
Recent advances in the study of exchange couplings in magnetic films are introduced.To provide a comprehensive understanding of exchange coupling,we have designed different bilayers,trilayers and multilayers,such as anisotropic hard/soft-magnetic multilayer films,ferromagnetic/antiferromagnetic/ferromagnetic trilayers,[Pt/Co]/NiFe/NiO heterostructures,Co/NiO and Co/NiO/Fe trilayers on an anodic aluminum oxide(AAO) template.The exchange-coupling interaction between soft-and hard-magnetic phases,interlayer and interfacial exchange couplings and magnetic and magnetotransport properties in these magnetic films have been investigated in detail by adjusting the magnetic anisotropy of ferromagnetic layers and by changing the thickness of the spacer layer,ferromagnetic layer,and antiferromagnetic layer.Some particular physical phenomena have been observed and explained. 相似文献
17.
Changjun Jiang Desheng Xue Wenbo Sui 《Journal of magnetism and magnetic materials》2010,322(22):3676-3679
Effective anisotropy of the ferromagnetic pinned layer of ferro(FM)-antiferromagnetic (AF)-coupled NiFe(FM)/FeMn(AF) exchange-biased system was investigated in a broad frequency range (100 MHz-5 GHz) using a complex permeability spectrum. The exchange bias and effective uniaxial anisotropy fields of the thin film have been computed theoretically using the Landau-Lifschitz-Gilbert (LLG) equation. From the measurements, uniaxial anisotropy of the pinned FM layer has been extracted to understand the nature of the exchange bias in the system. It is found that the uniaxial anisotropy field of NiFe layer when exchange biased with the AF layer increases from 5 to 15 Oe at different external magnetic fields. 相似文献
18.
In this study, the influences of thin film thickness and post-annealing process on the magnetic properties of CoFeB thin films were investigated. The angular dependency and linewidth of the ferromagnetic resonance signal were used to explore the magnetic behavior of sputtered single-layer and trilayer thin film stacks of CoFeB. A micromagnetic simulation model was employed based on the metropolis algorithm comprising the demagnetizing field and in-plane induced uniaxial anisotropy terms with all relevant contributions. Our results reveal that the direction of magnetization changes from in-plane to out-of-plane as a result of the annealing process and induces a perpendicular magnetic anisotropy in the 1-nm thick CoFeB thin film. The ferromagnetic resonance (FMR) linewidth can be defined well by the intrinsic Gilbert damping effect and the magnetic inhomogeneity contribution in both as-grown and annealed samples. The difference between the linewidths of the single and trilayer film is mainly caused by the spin pumping effect on damping which is associated with the interface layers. 相似文献
19.
20.
《Journal of magnetism and magnetic materials》2001,237(2):206-214
Computer simulation in a single domain multilayer model is used to investigate magnetization flop in magnetic tunnel junctions, exchange-biased by pinned synthetic antiferromagnets with the multilayer structure NiFe/AlOx/Co/Ru/Co/FeMn. The resistance to magnetization flop increases with decreasing cell size due to increased shape anisotropy and hence increased coercivity of the Co layers in the synthetic antiferromagnet. However, when the synthetic antiferromagnet is not or weakly pinned, the magnetization directions of the two layers sandwiching AlOx, which mainly determine the magnetoresistance, are aligned antiparallel due to a strong magnetostatic interaction, resulting in an abnormal MR change from the high MR state to zero, irrespective of the direction of the free layer switching. This emphasizes an importance of a strong pinning of the synthetic antiferromagnet at small cell dimensions. The threshold field for magnetization flop is found to increase linearly with increasing antiferromagnetic exchange coupling between the two Co layers in the synthetic antiferromagnet. The restoring force from magnetization flop to the normal synthetic antiferromagnetic structure is roughly proportional to the resistance to magnetization flop. Irrespective of the magnetic parameters and cell sizes, the state of magnetization flop does not exist near Ha=0, indicating that magnetization flop is driven by the Zeeman energy. 相似文献