Dispersion of Faraday rotation in Co/SiO2 multilayer films

The Faraday rotation spectra of Co/SiO₂ multilayer films were found to be substantially different from the well-known spectra of homogeneous Co films. The character of these changes was studied as a function of the thicknesses of the ferromagnetic metal and the nonmagnetic dielectric layers. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 4, 256–259 (25 February 1996)     

Ferromagnetic and spin-wave resonance in Co/Pd/CoNi multilayer films

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 d_Pd<d _c and equals zero at d_Pd>d _c (d _c is the characteristic length).     

Thickness dependent magnetization dynamics of perpendicular anisotropy Co/Pd multilayer films

We present the measurements of the picosecond magnetization dynamics of Co/Pd multilayer films. The dynamic magnetization properties of sputtered multilayer films were analyzed as a function of Co layer thicknesses and applied bias field. Both the eigenfrequencies of the magnetization precession in the multilayers and the associated Gilbert damping exhibit extreme sensitivity to the magnetic layer thickness on an atomic monolayer scale. The eigenfrequency increases more than threefold when the Co thickness decreases from 7.5 to 2.8 Å, mainly due to the changes in effective saturation magnetization and perpendicular anisotropy constant. A concomitant 2.6-fold increase in the damping of the oscillations is observed and attributed to stronger interface dissipation in thinner Co layers. In addition, we introduce a quasi-1D micromagnetic model in which the multilayer stack is described as a one-dimensional chain of macrospins that represent each Co layer. This model yields excellent agreement with the observed resonance frequencies without any free parameters, while being much simpler and faster than full 3D micromagnetic modeling.     

Experimental study of the energy gap in the spin-wave spectrum in Co/Pd multilayer films

The energy gap appearing in the spin-wave spectrum as a result of Bragg scattering by the modulation period q=2π/(d ₁+d ₂) of a one-dimensional superlattice is observed by the method of spin-wave resonance in Co/Pd multilayer films. It is shown that this gap is asymmetric: The “positive” deviation is from two to three times greater than the “negative” deviation. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 12, 938–941 (25 June 1996)     

Faraday effect in Co/TiO2 films

It is shown that in a layered medium consisting of a magnetic metal (Co) and a nonmagnetic insulator (TiO₂), the layer thickness being less than the wavelength of the light, a fundamental change occurs in the character of the Faraday-effect spectra if the number of layers is sufficiently large. When the number of pairs of layers changes from 5 to 10, a maximum appears near ~ 1.7 eV in the Faraday rotation spectrum and the ellipticity passes through zero. The results obtained are compared with the existing theory of the Faraday effect in granular structures consisting of a magnetic metal and nonmagnetic insulator. The surface plasmon energy in thin Co layers is estimated. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 7, 531–534 (10 April 1997)     

Spin-wave resonance in multilayer FeNiP/Pd films

Ferromagnetic and spin wave resonances are studied in FeNiP/Pd multilayer films obtained via chemical vapor deposition. The partial exchange interaction constant of polarized Pd films is found to be A _Pd ≈ 1 × 10^?7 erg/cm.     

Magnetooptical properties of Fe/Pd multilayer films

Multilayer films of Fe(x)/Pd(30 Å) (6≤x≤30 Å) are investigated with the help of the transversal Kerr effect (TKE) with incident light in the energy range 1.3–3.6 eV. Oscillations of the TKE depending on the thickness of the iron layer are revealed. The off-diagonal element of the dielectric tensor ? ₂ ^′ is calculated using themeasured values of the TKE for two incidence angles of light and the optical constants of all samples. It is shown that the quantity ? ₂ ^′ ω² (where ω is the frequency of incident light), which is proportional to the interband density of states, also oscillates, and its oscillations are similar in character to oscillations of the Kerr effect. The observed oscillatory dependence of the TKE and of the interband density of states are related to the manifestation of quantum confinement effects.     

Co/Pd and Co/Pd/CoNi multilayer films: Determination of the sign and magnitude of the exchange interaction of ferromagnetic layers separated by palladium layers

It is found that the exchange interaction of Co (5 nm)ferromagnetic layers via Pd in Co/Pd multilayer films and of Co (5 nm)and CoNi (5 nm) layers via the same nonmagnetic metal in Co/Pd/CoNi films can be both ferro-and antiferromagnetic. The period of the AF-F-AF oscillations is of the order of 0.8 nm, and the amplitude of the oscillations decays as a power-law function ~d _Pd ⁻² . Pis’ma Zh. éksp. Teor. Fiz. 66, No. 7, 487–491 (10 October 1997)     

基于多层膜偏振元件的软X射线磁光Faraday偏转测量

在北京同步辐射装置(BSRF)的3W1B软X射线光束线上利用自行研制的同步辐射软X射线综合偏振测量装置对Ni的M_2,3边附近(60—70 eV)进行了软X射线磁光(magneto-optical)法拉第效应(Faraday effect)的偏转测量,实验装置主要由起偏器,检偏器,样品架,圆形钕铁硼永磁铁和MCP探测器组成,偏振元件(起偏元件和检偏元件)均采用反射式非周期性Mo/Si宽带多层膜.实验采用反射起偏和反射检偏的模式,得到一系列能量范围在60—70 eV间的法拉第偏转角结果, 关键词： 软X射线 磁光Faraday效应 综合偏振测量装置 宽带多层膜     

Influence of layer thickness on the structure and the magnetic properties of Co/Pd epitaxial multilayer films

Co/Pd epitaxial multilayer films were prepared on Pd(111)_fcc underlayers hetero-epitaxially grown on MgO(111)_B1 single-crystal substrates at room temperature by ultra-high vacuum RF magnetron sputtering. In-situ reflection high energy electron diffraction shows that the in-plane lattice spacing of Co on Pd layer gradually decreases with increasing the Co layer thickness, whereas that of Pd on Co layer remains unchanged during the Pd layer formation. The CoPd alloy phase formation is observed around the Co/Pd interface. The atomic mixing is enhanced for thinner Co and Pd layers in multilayer structure. With decreasing the Co and the Pd layer thicknesses and increasing the repetition number of Co/Pd multilayer film, stronger perpendicular magnetic anisotropy is observed. The relationships between the film structure and the magnetic properties are discussed.     

Magnetic resonance in multilayer Gd/Si/Co magnetic films

The magnetic properties of multilayer Gd/Si/Co magnetic films are experimentally studied by electron magnetic resonance and analyzed theoretically. The introduction of a semiconductor silicon interlayer is found to substantially affect the magnetic interlayer coupling and the magnetic dynamics of the system. The interlayer coupling is shown to be ferromagnetic for the (Gd/Si)_n films and to be antiferromagnetic for the (Gd/Si/Co/Si)_n films. The temperature dependences of the exchange parameters and the gyromagnetic ratios are determined. Possible mechanisms responsible for the formation of the interlayer coupling are discussed.     

Structural ordering and self-organization effects in multilayer Pd/Fe films

The structural features of the distribution of Pd and Fe atoms in multilayer films derived via Penning-discharge sputtering are studied. The preparation of films is a highly nonequilibrium process; at the same time, it is relatively simple in terms of possible structural implementations, which are shown during the self-organization of sputtered atoms through the formation of clusters with an individual ordered structure. It is important that the “dynamic chaos” that appears during sputtering is stabilized during crystallization, which makes it possible to study the resulting structures using nondestructive inspection methods with fairly wide possibilities. Therefore, it is of interest to study self-organization during the sputtering of multilayer films in order to reveal the mechanisms of cluster formation and to simulate them. It is also shown that the self-organization during sputtering and subsequent crystallization is accompanied not only by the ordering in the form of clusters, buts also by an ordered arrangement of these clusters.     

Spin-valve magnetoresistive structures based on Co/Tb multilayer films

The effect of the layer thickness on the magnetic properties of {Co/Tb}_n, {Co/Tb}_n/Co, and {Co/Tb}_n/Co/Cu/Co multilayer films is studied. The dependence of the hysteresis and magnetoresistive properties of {Co(1 nm)/Tb(1 nm)}_n/Co(5 nm)/Cu(L _Cu)/Co(5 nm) structures on the thickness of the {Co/Tb}_n layer and copper spacing are obtained. The feasibility of spin-valve structures based on {Co/Tb}_n multilayer films with in-plane anisotropy is demonstrated.     

Structural and magnetic properties of Co-C composite films and Co/C multilayer films

CoC composite films and Co/C multilayer films have been prepared by a method incorporating ion beam sputtering and plasma chemical vapor deposition. It has been found that the structure and magnetic properties of both the Co-C composite and the Co/C multilayer films depend strongly on the substrate temperature during deposition. The Co-C composite film deposited at room temperature is amorphous, with relatively low saturation magnetization and coercivity. On the other hand, the film deposited at 250 °C is composed of fine Co crystallites separated by amorphous C or Co-C phase. As a result, both the saturation magnetization and coercivity are increased compared with the film deposited at room temperature. When deposited at room temperature, the Co/C multilayer film exhibits good periodicity, with a period of 70 nm (Co: 40 nm, C: 30 nm) and sharp and flat Co-C interfaces. High magnetization (602 emu/cm³) and low coercivity (1.6 Oe) are obtained for such a film. However, increasing the substrate temperature to 250 °C was found to be detrimental to the magnetic properties due to the formation of cobalt carbide at the Co-C interface. Received: 11 July 2000 / Accepted: 13 July 2000 / Published online: 30 November 2000     

Curie temperature oscillations and critical phenomena in Co/Cu multilayer films

A study is made of Co/Cu multilayer structures with ultrathin Co layers. Oscillations of the saturation magnetization and Curie temperature as a function of the thickness of the intermediate Cu conducting layer are observed. The behavior of the magnetization near the second-order phase transition is studied, and the critical exponents of the magnetization are determined. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 5, 341–345 (10 September 1996)     

Co/Ti金属磁性多层膜的激光布里渊散射研究(英文)

在室温下利用直流磁控溅射法制备出了具有不同Co层厚度的 [Co(dConm) /Ti(dTinm) ]n 金属磁性多层膜 (其中dCoanddTi是Co和Ti的厚度 ,n薄膜调制周期数 )。在 30 0K下用X射线衍射法 (XRD)和布里渊散射方法研究了Co层厚度分别为dCo=1 ,2 ,2 5 ,3 5nm ,Ti层厚度为dTi=2 5nm的Co/Ti多层膜。XRD的结果所示在Co/Ti多层膜中Co层厚度超过 2 5nm ,其结构类似块材Co的多晶结构。对比之下 ,Co/Ti多层膜中Co层厚度低于 2 5nm ,其XRD衍射峰随Co层厚度减少变的峰形加宽 ,衍射峰的强度减少 ,峰位移动和消失。在Co/Ti多层膜中自旋波的布里渊散射结果表明 :在Co/Ti多层膜中 ,对于dCo>2 5nm磁性呈铁磁性耦合 ,在dCo≤ 2 5nm时 ,其呈反铁磁性耦合。除表面自旋波外 ,在呈反铁磁性耦合的材料中观测到了两个有体特征的自旋波 ,而在呈铁磁耦合的材料中只观测到一个有体特征的自旋波。     

Magnetic Compton profiles of Fe thin film and anisotropy of Co/Pd multilayer

The magnetic Compton profiles (MCPs) of Fe thin film with 1 μm thickness have been successfully measured, using polyethylene terephtalate (PET) substrates with 4 μm thickness to reduce scattering photons from substrate.We have succeeded for the first time to observe the anisotropy of MCPs in the Co/Pd multilayer. The magnetic out-of-plane anisotropy of the current Co (0.8 nm)/Pd (1.6 nm) multilayer sample can be explained by the model of a large number of the |m|=1 states of 3d-bands.     

Magnetic circular dichroism of [Co/Pd] and [CoB/Pd] multilayered films

Magnetic circular dichroism (MCD) and X-ray absorption spectra (XAS) at the Co L_2,3-edge of [Co/Pd]₂₀ and [CoB/Pd]₂₀ multilayered films, which were fabricated at 260 °C with different magnetic layer thicknesses (δ), have been measured. The lineshapes of XAS–MCD show that the electronic state of Co 3d of the films hardly changes even when sputtered at higher temperatures. The expectation values of orbital and spin angular momentum (〈L_z〉 and 〈S_z〉) are estimated using the sum rule, and it is found that 〈L_z〉/〈S_z〉 in δ<0.5 nm is larger than that in δ>0.5 nm.     

Faraday rotation in gadolinium orthochromite

Faraday rotation and linear birefringence of GdCrO₃ were measured in the spectral range 0.8 to 2.0 μm at liquid nitrogen temperature. Good agreement is obtained between the experimental data and the theoretical values of rotation, calculated by the use of the formula describing Faraday rotation in the presence of the linear birefringence. The intrinsic Faraday rotation as a function of the wavelength is determined and it is probably due to higher-energy optical transitions.     

Faraday rotation in Eu chalcogenides

We have performed a calculation of Verdet's constant for Eu chalcogenides, based on the assumption that the important electronic transitions are from localized 4? orbitals to Block-like 5d states. The results are in fair agreement with experiment for EuSe.