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1.
The influence of the Cu capping layer thickness on the spin pumping effect in ultrathin epitaxial Co and Ni films on Cu(0 0 1) was investigated by in situ ultrahigh vacuum ferromagnetic resonance. A pronounced increase in the linewidth is observed at the onset of spin pumping for capping layer thicknesses dCu larger than 5 ML, saturating at dCu = 20 ML for both systems. The spin mixing conductance for Co/Cu and Ni/Cu interfaces was evaluated.  相似文献   

2.
The peculiarities of absorption of rf electromagnetic radiation (ferromagnetic resonance) in multilayer NiFe/Ni0.65Cu0.35(d)/CoFe structures in a wide temperature range are analyzed. It is shown that the type of interaction of the NiFe and CoFe ferromagnetic films via a “weak” ferromagnetic Ni0.65Cu0.35 interlayer changes from antiferromagnetic to ferromagnetic upon cooling and a decrease in interlayer thickness d. The detected temperature dependence of the interlayer interaction indicates the possibility of observation of a strong magnetocaloric effect in the structures under investigation.  相似文献   

3.
It has been found that the magnitude and sign of exchange interaction between Co(5 nm) and CoNi(5 nm) ferromagnetic layers through Pd depend on magnetization orientation of ferromagnetic layers. If magnetization is oriented in a layer plane, exchange interaction can be both ferromagnetic and antiferromagnetic. If magnetization orientation is orthogonal to a layer plane, the exchange constant is always positive at dPd<d c and equals zero at dPd>d c (d c is the characteristic length).  相似文献   

4.
By varying the Pd thickness (tPd) from 0 to 8 nm in [Co/Pd]4/Co/Pd(tPd)/NiFe exchange springs, we demonstrate (i) continuous tailoring of the exchange coupling between a [Co/Pd]4/Co layer with perpendicular anisotropy, and a NiFe layer with an in-plane easy axis, (ii) tuning of the NiFe out-of-plane magnetization angle from 20 to 80, and (iii) an up to two-fold increase in the NiFe damping. The partial decoupling also results in a highly uniform NiFe magnetization. These properties make [Co/Pd]4/Co/Pd(tPd)/NiFe spring magnets ideal candidates for use as tilted polarizers, by combining stable and well-defined spin directions of its carriers with a high degree of angular freedom.  相似文献   

5.
A new class of magnetic compounds has been discovered in the temary system Mn-X-Bi where X is Ni, Cu, Rh or Pd. The approximate compositions of these compounds are Mn5Ni2Bi4, Mn3Cu4Bi4, Mn5Rh2Bi4, and Mn5Pd2Bi4. The Bravais lattice is face-centered cubic, and the lattice constants are 12.16 Å (X = Ni), 12.18 Å (X = Cu), 12.31 Å (X = Rh) and 12.44 Å (X = Pd). These compounds are probably ferromagnetic and have Curie temperatures in the range -7°C to 183°C. A crystal structure is proposed for these compounds which contains 88 atoms/unit cell.  相似文献   

6.
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   

7.
A systematic investigation has been done on the correlation between texture, grain size evolution and magnetic properties in Ta/Ni81Fe19/Ir20Mn80/Co90Fe10/Ta exchange bias in dependence of Ta buffer and NiFe seed layer thickness in the range of 2-10 nm, deposited by pulsed DC magnetron sputtering technique. A strong dependence of 〈1 1 1〉 texture on the Ta/NiFe thicknesses was found, where the reducing and increasing texture was correlated with exchange bias field and unidirectional anisotropy energy constant at both NiFe/IrMn and IrMn/CoFe interfaces. However, a direct correlation between average grain size in IrMn and Hex and Hc was not observed. L12 phase IrMn3 could be formed by thickness optimization of Ta/NiFe layers by deposition at room temperature, for which the maximum exchange coupling parameters were achieved. We conclude finally that the coercivity is mainly influenced by texture induced interfacial effects at NiFe/IrMn/CoFe interfaces developing with Ta/NiFe thicknesses.  相似文献   

8.
The superconducting and magnetic properties of Nb/Pd1-xFex/Nb triple layers with constant Nb layer thickness dNb=200 ? and different interlayer thicknesses 3 ?≤ dPdFe ≤ ? are investigated. The thickness dependence of the magnetization and of the superconducting transition temperature shows that for small iron concentration x the Pd1-xFex layer is likely to be in the paramagnetic state for very thin films whereas ferromagnetic order is established for x ≥ 0.13. The parallel critical field Bc2||(T){B_{c2||}}(T) exhibits a transition from two-dimensional (2D) behavior where the Nb films are coupled across the interlayer, towards a 2D behavior of decoupled Nb films with increasing dPdFeand/or x. This transition allows a determination of the penetration depth xF{\xi _F} of Cooper pairs into the Pd1-xFex layer as a function of x. For samples with a ferromagnetic interlayer xF{\xi _F} is found to be independent of x.  相似文献   

9.
Oscillating behavior of superconductivity in ultrathin bilayers of niobium and ferromagnetic alloy Cu41Ni59 has been observed. This phenomenon was most pronounced at a Nb layer thickness of about 7.3 nm: the superconducting transition temperature T c first sharply decreased with an increase in the ferromagnetic alloy thickness to complete suppression of superconductivity at the ferromagnetic alloy thickness d CuNi ≈ 4 nm. With a further increase in the thickness d CuNi, the superconductivity was restored at d CuNi ≥ 13 nm. This strongly nonmonotonic and reentrant behavior of superconductivity in Nb/Cu41Ni59 bilayers is attributed to implementation of a state in the ferromagnetic alloy that is similar to the quasi-one-dimensional Fulde-Ferrell-Larkin-Ovchinnikov state.  相似文献   

10.
The standing spin wave spectra of Ni0.8Fe0.2(1000–3000 Å)/(Dy1?x Cox(700 Å) bilayer exchange-biased films with two different (precompensation Dy0.2Co0.8 and postcompensation Dy0.3Co0.7) compositions of the hard magnetic layer are analyzed. Measurements are performed at room temperature. It is found that the effective magnetic layer thickness (d eff=d 0±Δd), which determines the wave vectors of the first modes in the spectrum, differs from the d 0 value specified in film technology. The sign of |Δd| ~ 500 Å is governed by the composition of the DyCo hard magnetic layer.  相似文献   

11.
The proximity effect was studied in a thin-film Fe-Cr-V-Cr-Fe layered system. As the chromium layer thickness (dCr) increases at a fixed thickness of iron layers (dFe), the dependence of the superconducting transition temperature (Tc) on dCr exhibits a maximum at dCr ? 40 Å followed by a sharp decrease. Investigation of the dependence of Tc on dFe at a fixed dCr showed that the depth of penetration of the Cooper pairs into a chromium layer does not exceed 40 Å. Analysis of the results obtained suggests that, at dCr ? 40 Å, chromium layers exhibit the transition from a nonmagnetic state to an incommensurate spin density wave state.  相似文献   

12.
The effect of atomic disordering and alloying with d elements (Fe, Pd, Cu) on the transport and magnetic properties of Cu3Pd alloys has been investigated at low temperatures (T < 80 K) in strong magnetic fields (H ≤ 8 MA/m). The specific features of the crystal structure and temperature and field dependences of the electrical resistance, magnetoresistance, Hall effect, and magnetic susceptibility of Cu72Pd28, Cu75Pd25, Cu80Pd20 and Cu74.5Pd24.5Fe1 alloys are discussed.  相似文献   

13.
The effect of the exchange energy variation in weakly ferromagnetic alloys on the superconducting resistive transition of superconductor/ferromagnet/superconductor (S/F/S) trilayers is studied. Critical temperature, T c , and resistive transitions versus the F-layer thickness, d F , have been analyzed in Nb/Cu0.41Ni0.59/Nb and Nb/Pd0.81Ni0.19/Nb trilayers. We show that T c (d F ) dependence is sensitive to magnetic inhomogeneities in the F-layer for values of d F corresponding to thickness range where the π-superconducting state is established.  相似文献   

14.
采用磁控溅射法制备了Pd/Fe和Pd1-xFex/Fe多层膜.利用变换梯度磁强计测量了样品的Ms.发现层间耦合是铁磁性的,Ms具有长程振荡,周期为4ML.振荡的相位和周期在Pd0.966Fe0.034/Fe和Fd0.944Fe0.056/Fe系统中保持不变.就Pd/Fe多层膜中是否存在内层的Pd负极化和长程的铁磁耦合振荡进行了讨论,并分析了不同计算结果以及理论计算与实验结果之间存在差异的原因. 关键词:  相似文献   

15.
The variation of hyperfine field, isomer shift and Curie temperature with chromium concentration has been studied for the alloys (NiFe)1?xCrx for x = 0, 5, 10 and 15 at .%. The decrease in hyperfine field and isomer shift suggests an emptying of the majority spin d-band with increasing Cr concentration (reducing number of average 3d + 4s electrons per atom). The Curie temperature is also found to reduce rapidly with Cr concentration in agreement with magnetisation data. But the Curie temperatures as determined from Mössbauer spectra are considerably lower than those given by magnetisation studies and for the 10 and 15 at .% Cr concentrations the magnetic transition is spread out over a range of temperatures suggesting a mictomagnetic behaviour.  相似文献   

16.
王一军  刘洋  于广华 《物理学报》2012,61(16):167503-167503
在铁磁层(FM)/反铁磁层(FeMn)耦合体系中插入Pt 插层或对靠近FM/FeMn界面处的FeMn掺杂Pt元素,研究了体系的交换偏置场 Hex及矫顽力Hc随Pt插层深度 dPt与Pt掺杂层厚度tPtFeMn的变化关系. 实验结果表明,引入Pt插层后NiFe/FeMn(dPt)/Pt/FeMn体系的未补偿磁矩(UCS)的数量得到很大的提高,从而对HexHc 起到增强的作用; 同时, 从实验结果可以推测FeMn层内部UCS的分布深度约为1.3 nm. 另外,对靠近FM/FeMn界面处的FeMn掺杂Pt元素,发现掺入Pt元素后体系的Hex 得到有效增强, 这是因为掺入Pt元素后体系UCS的数量也得到很大的提高.  相似文献   

17.
Magnetic and superconducting properties of Fe/Nb epitaxial bilayers have been studied. Single crystal Fe/Nb (110) bilayers with a Nb thicknessd Nb in the range from 250 to 650 Å and with a Fe thicknessd Fe in the range from 7 to 27 Å were prepared using molecular beam epitaxy techniques. Magnetization measurements showed the existence of a magnetically “dead” Fe-interface layer with a thicknessd NM varying strongly with minor modifications of the growth conditions. For bilayers with a small magnetic layer thicknessd M and a smalld NM the FMR measurements revealed an anomalous decrease of the effective magnetization 4πM eff of the ferromagnetic Fe layer below the superconducting transition temperatureT c. The absolute change of 4πM eff belowT c depends strongly on the actual values ofd M andd NM: upon decreasing bothd M andd NM the effect increases considerably. As a possible mechanism for the anomalous temperature dependence of 4πM eff belowT c we discuss a spatial modulation of ferromagnetic order due to a modification of the RKKY inter-action in the superconducting state.  相似文献   

18.
The onset of ferromagnetic order in TiBe2-xCux alloys, with x = 0.5, 0.4, 0.3, 0.2 and 0.15, has been examined using the technique of neutron small-angle scattering. The Curie temperature, Tc, for these alloys has been determined from the temperature dependence of the magnetic critical scattering. A linear extrapolation of Tc versus copper concentration yields a critical concentration for ferromagnetic order of xc = 0.05 ± 0.02. For the alloys with x = 0.4, 0.5 the lineshape of the magnetic critical scattering, at and above Tc, is well explained by the Ornstein-Zernicke form of the spin correlation function. For the lower concentration alloys the exact form of the spin correlation function is still unclear.  相似文献   

19.
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   

20.
The spin wave spectrum of chemically disordered Pd0.5Fe0.5 has been determined by neutron inelastic scattering. At small wavevectors, the dispersion curve is quadratic and isotropic with a spin wave stiffness constant of 47.9 ± 3.3 THz Å2, at room temperature. There is little sign of the anisotropic behaviour observed in the ordered alloy Pd3Fe.  相似文献   

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