Showing papers on "Magnetic anisotropy published in 2001"

Magnetic Anisotropy of a Single Cobalt Nanocluster

Abstract: Using a new micro-SQUID setup, we investigate magnetic anisotropy in a single 1000-atom cobalt cluster. This system opens new fields in the characterization and understanding of the origin of magnetic anisotropy in such nanoparticles. For this purpose, we report three-dimensional switching field measurements performed on a 3 nm cobalt cluster embedded in a niobium matrix. We are able to separate the different magnetic anisotropy contributions and evidence the dominating role of the cluster surface.

Magnetic Ordering in an Organic Polymer

Abstract: We describe preparation and magnetic properties of an organic pi-conjugated polymer with very large magnetic moment and magnetic order at low temperatures. The polymer is designed with a large density of cross-links and alternating connectivity of radical modules with unequal spin quantum numbers (S), macrocyclic S = 2 and, cross-linking S = (1/2) modules, which permits large net S values for either ferromagnetic or antiferromagnetic exchange couplings between the modules. In the highly cross-linked polymer, an effective magnetic moment corresponding to an average S of about 5000 and slow reorientation of the magnetization by a small magnetic field (less than or equal to 1 oersted) below a temperature of about 10 kelvin are found. Qualitatively, this magnetic behavior is comparable to that of insulating spin glasses and blocked superparamagnets.

Magnetization reversal due to vortex nucleation, displacement, and annihilation in submicron ferromagnetic dot arrays

Abstract: Magnetization processes are analytically described for the arrays of soft ferromagnetic polycrystalline circular dots with submicron dimensions, wherein the magnetization reversal accompanied by nucleation, displacement, and annihilation of magnetic vortices. Magnetostatic, exchange, and Zeeman energies are taken into account for the analysis. The magnetic state of each dot in an applied magnetic field is treated as an off-centered rigid vortex structure; i.e., the vortex keeps its spin distribution while being displaced. This rigid vortex model yields analytical expressions for the size-dependent initial susceptibility, the vortex nucleation, and the annihilation fields. The interdot magnetostatic interaction plays an important role in the magnetization reversal for the arrays when the interdot distance is smaller than the disk radius, where the initial susceptibility increases and both the nucleation and annihilation fields decrease. The analytical predictions are compared to the micromagnetic calculations, and limitations of the model are discussed.

Dipolar interactions in arrays of nickel nanowires studied by ferromagnetic resonance

Abstract: Using a planar microstrip transmission line, the dipolar interactions in electrodeposited Ni nanowires arrays an characterized as a function of the membrane porosity (4% to 38%) and the wire diameter (56 to 250 nm). The dipolar interactions between the wires can be modeled in a mean-field approach as an effective uniaxial anisotropy field oriented perpendicular to the wire axis and proportional to the membrane porosity. The dipolar interaction field opposes the self-demagnetization field of an isolated single wire which keeps the magnetization parallel to the wire axis. An increase in the porosity therefore induces a switching of the effective anisotropy easy axis from parallel to perpendicular to the win axis above a critical porosity of 35-38% independent of the wire diameter.

Theory of magnetic anisotropy in III 1 − x Mn x V ferromagnets

Abstract: We present a theory of magnetic anisotropy in ${\mathrm{III}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{V}$-diluted magnetic semiconductors with carrier-induced ferromagnetism. The theory is based on four- and six-band envelope function models for the valence-band holes and a mean-field treatment of their exchange interactions with ${\mathrm{Mn}}^{++}$ ions. We find that easy-axis reorientations can occur as a function of temperature, carrier density p, and strain. The magnetic anisotropy in strain-free samples is predicted to have a ${p}^{5/3}$ hole-density dependence at small p, a ${p}^{\ensuremath{-}1}$ dependence at large p, and remarkably large values at intermediate densities. An explicit expression, valid at small p, is given for the uniaxial contribution to the magnetic anisotropy due to unrelaxed epitaxial growth lattice-matching strains. Results of our numerical simulations are in agreement with magnetic anisotropy measurements on samples with both compressive and tensile strains. We predict that decreasing the hole density in current samples will lower the ferromagnetic transition temperature, but will increase the magnetic anisotropy energy and the coercivity.

Perpendicular exchange bias of Co/Pt multilayers.

Abstract: Exchange bias measurements of ferromagnetic/antiferromagnetic (F/AF) bilayers are typically performed with the magnetization of the F layer parallel to the AF interface. We describe measurements of Co/Pt multilayers with out-of-plane magnetic easy axis that are exchange biased with CoO. Field-cooling experiments with the applied field perpendicular and parallel to the sample plane exhibit loop shifts and enhanced coercivities. Modeling and comparison to biasing of samples with planar easy axis suggests such measurements provide a way to probe the spin projections at F/AF interfaces.

Field-dependent surface impedance tensor in amorphous wires with two types of magnetic anisotropy: helical and circumferential

Abstract: This paper concerns the theoretical and experimental investigation of the magnetoimpedance (MI) effect in amorphous wires in terms of the surface impedance tensor $\stackrel{^}{\ensuremath{\varsigma}}.$ Physical concepts of MI and problems of significant practical importance are discussed using the results obtained. The theoretical analysis is based on employing the asymptotic-series-expansion method of solving the Maxwell equations for a ferromagnetic wire with an ac permeability tensor of a general form associated with magnetization rotation. The magnetic-structure-dependent impedance tensor $\stackrel{^}{\ensuremath{\varsigma}}$ is calculated for any frequency and external magnetic field, and is not restricted to the case when only strong skin effect is present. This approach allows us to develop a rigorous quantitative analysis of MI characteristics in wires, depending on the type of magnetic anisotropy, the magnitude of dc bias current, and an excitation method. The theoretical model has been tested by comparing the obtained results with experiment. For the sake of an adequate comparison, the full tensor $\stackrel{^}{\ensuremath{\varsigma}}$ is measured in CoFeSiB and CoSiB amorphous wires having a circumferential and helical anisotropy, respectively, by determining the ${S}_{21}$ parameter. In cases when the rotational dynamics is responsible for the impedance behavior, there is a reasonable agreement between the experimental and theoretical results. Such effects as the ac biased asymmetrical MI in wires with a circumferential anisotropy, and the transformation in MI behavior caused by a dc current (from that having a symmetric hysteresis to an asymmetric anhysteretic one) in wires with a helical anisotropy are discussed.

Magnetoresistance effect element, magnetic head, magnetic head assembly, magnetic storage system

Abstract: Disclosed are a high-sensitivity and high-reliability magnetoresistance effect device (MR device) in which bias point designing is easy, and also a magnetic head, a magnetic head assembly and a magnetic recording/reproducing system incorporating the MR device. In the MR device incorporating a spin valve film, the magnetization direction of the free layer is at a certain angle to the magnetization direction of a second ferromagnetic layer therein when the applied magnetic field is zero. In this, the pinned magnetic layer comprises a pair of ferromagnetic films as antiferromagnetically coupled to each other via a coupling film existing therebetween. The device is provided with a means of keeping the magnetization direction of either one of the pair of ferromagnetic films constituting the pinned magnetic layer, and with a nonmagnetic high-conductivity layer as disposed adjacent to a first ferromagnetic layer on the side opposite to the side on which the first ferromagnetic layer is contacted with a nonmagnetic spacer layer. With that constitution, the device has extremely high sensitivity, and the bias point in the device is well controlled.

Magnetic spin polarisation and magnetisation rotation device with memory and writing process, using such a device

Abstract: A magnetic spin polarizing a magnetization rotation device with a memory and a writing process using such a device. The device is configured to include an apparatus for polarizing the spin of electrons, including a magnetic layer having magnetization perpendicular to the plane of magnetization of respective first and second magnetic layers. The magnetization of the second magnetic layer rotates within a plane, which is either the plane of the layer or a perpendicular plane.

Three-layered stacked magnetic spin polarization device with memory

Abstract: A magnetic device including at least a memory cell having a first magnetic layer with a fixed magnetization direction. The first magnetic layer spin polarizes a writing current of electrons. The memory cell includes a second magnetic layer having a three-layered stack with a variable magnetization direction. An insulating or semi-conduction layer is formed between the first and second magnetic layers. The variable magnetization direction is oriented by spins of a spin polarized writing current. The three-layered stack includes two magnetic layers separated by a non-magnetic conducting layer. The first magnetic layer aligns the variable magnetization direction with the fixed magnetization direction by directing an incident writing current of electrons perpendicular through the first magnetic layer and then perpendicular through the second magnetic layer. The first magnetic layer opposes the variable magnetization direction with the fixed magnetization direction by directing another incident writing current of electrons perpendicular through the second magnetic layer and then perpendicular through the first magnetic layer to.

Magnetic anisotropy and domain patterns in electrodeposited cobalt nanowires

Abstract: The magnetic anisotropy and domain structure of electrodeposited cylindrical Co nanowires with length of 10 or 20 μm and diameters ranging from 30 to 450 nm are studied by means of magnetization and magnetic torque measurements, as well as magnetic force microscopy. Experimental results reveal that crystal anisotropy either concurs with shape anisotropy in maintaining the Co magnetization aligned along the wire or favours an orientation of the magnetization perpendicular to the wire, hence competing with shape anisotropy, depending on whether the diameter of the wires is smaller or larger than a critical diameter of 50 nm. This change of crystal anisotropy, originating in changes in the crystallographic structure of Co, is naturally found to strongly modify the zero (or small) field magnetic domain structure in the nanowires. Except for nanowires with parallel-to-wire crystal anisotropy (very small diameters) where single-domain behaviour may occur, the formation of magnetic domains is required to explain the experimental observations. The geometrical restriction imposed on the magnetization by the small lateral size of the wires proves to play an important role in the domain structures formed.

Coercivity in exchange-bias bilayers

Abstract: A model is presented for coercivity in polycrystalline exchange-bias bilayers. It includes two contributions for their enhanced coercivity, inhomogeneous reversal, and irreversible transitions in the antiferromagnetic grains. The model can be characterized in terms of a small number of dimensionless parameters, and its behavior has been determined through simulations of magnetic reversal for a range of values of these parameters. In these simulations, the first contribution to the coercivity arises from energy losses in the ferromagnet due to irreversible transitions over small, local energy barriers in the ferromagnetic film due to the inhomogeneous coupling to the antiferromagnet. This inhomogeneous reversal contributes to the coercivity at all temperatures. The second contribution to the coercivity arises from energy losses in the antiferromagnet due to irreversible transitions of the antiferromagnetic order in the grains. In the present model, the antiferromagnetic order only becomes unstable at nonzero temperature, so that this contribution to the coercivity only occurs at nonzero temperatures. In addition to the coercivity, the computed hysteresis loops are found to be asymmetric, and the loop shift is shown to differ from the grain-averaged unidirectional anisotropy.

Magnetic switching of single vortex permalloy elements

Abstract: Magnetic vortices play an important role in the switching behavior of micron- and submicron-sized ferromagnetic elements. We have prepared submicron permalloy elements by a combination of electron-beam lithography and liftoff technique on electron transparent membrane substrates. The magnetization reversal mechanism and the remanent magnetization configuration were observed by means of Lorentz transmission electron microscopy. In remanence, the investigated structures form a vortex configuration. In situ magnetizing experiments showed the possibility of adjusting the sense of magnetization rotation by introducing a slight geometric asymmetry to the otherwise circular nanostructures.

Large magnetocrystalline anisotropy in bilayer transition metal phases from first-principles full-potential calculations

Abstract: The computational framework of this study is based on the local-spin-density approximation with first-principles full-potential linear muffin-tin orbital calculations including orbital polarization (OP) correction. We have studied the magnetic anisotropy for a series of bilayer CuAu(I)-type materials such as $\mathrm{Fe}X,$ $\mathrm{Mn}X(X=\mathrm{N}\mathrm{i},\mathrm{P}\mathrm{d},\mathrm{P}\mathrm{t}),$ CoPt, NiPt, MnHg, and MnRh in a ferromagnetic state using experimental structural parameters to understand the microscopic origin of magnetic-anisotropy energy (MAE) in magnetic multilayers. Except for MnRh and MnHg, all these phases show perpendicular magnetization. We have analyzed our results in terms of angular momentum-, spin- and site-projected density of states, magnetic-angular-momentum-projected density of states, orbital-moment density of states, and total density of states. The orbital-moment number of states and the orbital-moment anisotropy for $\mathrm{Fe}X$ $(X=\mathrm{N}\mathrm{i},\mathrm{P}\mathrm{d},\mathrm{P}\mathrm{t})$ are calculated as a function of band filling to study its effect on MAE. The total and site-projected spin and orbital moments for all these systems are calculated with and without OP when the magnetization is along or perpendicular to the plane. The results are compared with available experimental as well as theoretical results. Our calculations show that OP always enhances the orbital moment in these phases and brings them closer to experimental values. The changes in MAE are analyzed in terms of exchange splitting, spin-orbit splitting, and tetragonal distortion/crystal-field splitting. The calculated MAE is found to be in good agreement with experimental values when the OP correction is included. Some of the materials considered here show large magnetic anisotropy of the order of meV. In particular we found that MnPt will have a very large MAE if it could be stabilized in a ferromagnetic configuration. Our analysis indicates that apart from large spin-orbit interaction and exchange interaction from at least one of the constituents, a large crystal-field splitting originating from the tetragonal distortion is also a necessary condition for having large magnetic anisotropy in these materials. Our calculation predicts large orbital moment in the hard axis in the case of FePt, MnRh, and MnHg against expectation.

Coordination and chemical effects on the structural, electronic, and magnetic properties in Mn pnictides

Abstract: Simple structures of MnX binary compounds, namely hexagonal NiAs and zincblende, are studied as a function of the anion (X = Sb, As, P) by means of the all-electron FLAPW method within local spin density and generalized gradient approximations. An accurate analysis of the structural, electronic and magnetic properties reveals that the cubic structure greatly favours the magnetic alignment in these compounds leading to high magnetic moments and nearly half-metallic behaviour for MnSb and MnAs. The effect of the anion chemical species is related to both its size and the possible hybridization with the Mn $d$ states; both contributions are seen to hinder the magnitude of the magnetic moment for small and light anions. Our results are in very good agreement with experiment - where available - and show that the generalized gradient approximation is essential to correctly recover both the equilibrium volume and magnetic moment.

Magnetic properties of the MnBi intermetallic compound

Abstract: A MnBi alloy containing over 90 wt % low-temperature phase (LTP) has been obtained by high-temperature sintering and magnetic purification. The coercivity of the bonded MnBi magnet increases with increasing temperatures. A coercivity of 2.0 T has been achieved at 400 K. The maximum energy product (BH)max of the magnet is 7.7 MGOe (61 kJ/m3) and 4.6 MGOe (37 kJ/m3) at room temperature and 400 K, respectively. Neutron diffraction and magnetic data reveal a spin reorientation, which gives rise to low anisotropy fields and coercivity at lower temperatures for the LTP MnBi alloy.

Control of magnetization dynamics in Ni/sub 81/Fe/sub 19/ thin films through the use of rare-earth dopants

Abstract: We show that the magnetization dynamics of soft ferromagnetic thin films can be tuned using rare-earth (RE) dopants. Low concentrations (2 to 10%) of Tb in 50 nm Ni/sub 81/Fe/sub 19/ films are found to increase the Gilbert magnetic damping parameter /spl alpha/ over two orders of magnitude without great effect on easy axis coercivity or saturation magnetization. Comparison with Gd dopants indicates that the orbital character of the Tb moment is important for transferring magnetic energy to the lattice. Structural transformations from the crystalline to the amorphous state, observed over the first 2%-10% of RE doping, may play a contributing but not sufficient role in damping in these films. The approach demonstrated here shows promise for adjusting the dynamical response, from underdamped to critically damped, in thin film materials for magnetic devices.

Magnetic, magneto-optical, and structural properties of URhAl from first-principles calculations

Abstract: We present a first-principles investigation of the electronic properties of the intermetallic uranium compound URhAl. Two band-structure methods are employed in our study, the full-potential augmented plane-wave (FLAPW) method, in which the spin-orbit interaction was recently implemented, and the relativistic, non-full-potential, augmented-spherical-wave method. To scrutinize the relativistic implementation of the FLAPW method, we compare the spin and orbital moments on each atom, as well as the magneto-optical Kerr spectra, as calculated with both methods. The computed quantities are remarkably consistent. With the FLAPW method we further investigate the magnetocrystalline anisotropy energy, the x-ray magnetic circular dichroism at the uranium ${M}_{4,5}$ edge, the equilibrium lattice volume, and the bulk modulus. The magnetocrystalline anisotropy energy is computed to be huge, 34 meV per formula unit. The calculated uranium moments exhibit an Ising-like behavior---they almost vanish when the magnetization direction is forced to lie in the uranium planes. The origin of this behavior is analyzed. The calculated optical and magneto-optical spectra, and also the equilibrium lattice parameter and bulk modulus, are found to compare well to the available experimental data, which emphasizes the itinerant character of the $5f$'s in URhAl.

Epitaxial Spinel Ferrite Thin Films

Abstract: ▪ Abstract Recently there have been significant advances in understanding the magnetic properties of epitaxial ferrite films that are not found in bulk ferrites. Much effort has been expended on trying to achieve bulk properties in thin films for a wide range of applications. From a fundamental science perspective, epitaxial thin films and heterostructures have provided model systems in which novel phenomena, such as modified super-exchange interactions, nearly ideal exchange coupling, and perpendicular exchange coupling, have been observed. These magnetic phenomena and other anomalous magnetic properties are interesting in their own right and are highlighted here.

Tailoring exchange bias with magnetic nanostructures

Abstract: Exchange bias in antiferromagnet/ferromagnet bilayers can be tuned by their lateral dimensions when they are below typical magnetic domain sizes. Bilayers of uniform-${\mathrm{FeF}}_{2}$/nanoporous Fe-network have been successfully fabricated by a copolymer nanolithography technique. Feature sizes of about 200 \AA{} have been achieved over a macroscopic 1 ${\mathrm{cm}}^{2}$ area. Exchange bias larger than that in uniform ${\mathrm{FeF}}_{2}/\mathrm{F}\mathrm{e}$ film has been observed, with a similar temperature dependence. Magnetic hysteresis loops and anisotropic magnetoresistance both show pronounced asymmetry that vanishes at the ${\mathrm{FeF}}_{2}$ N\'eel temperature. The asymmetry is due to a magnetization rotation process that builds up moments perpendicular to the saturation magnetization directions. The characteristics of the exchange bias originates from the nanostructure of the bilayer.

Unusual ferromagnetic couplings in single end-to-end azide-bridged cobalt(II) and nickel(II) chain systems.

Abstract: Two new one-dimensional single azide-bridged metal(II) compounds [[M(5-methylpyrazole)4(N3)]n](ClO4)n(H2O)n [M = Co (1a), Ni (2a)] were prepared by treating an M(II) ion with stoichiometric amount of sodium azide in the presence of four equivalents of the 3(5)-methylpyrazole ligand. The isostructural compounds 1a and 2a crystallize in the monoclinic space group P2(1)/n. The azide bridging ligands have a unique end-to-end coordination mode that brings two neighboring metal centers into a cis-position with respect to the azide unit to form single end-to-end azide-bridged cobalt(II) and nickel(II) chains. The two neighboring metal atoms at inversion centers adopt octahedral environments with four equatorial 3(5)-methylpyrazole ligands and two axial azide bridges. Two adjacent equatorial least-squares planes form dihedral angles of 60.5 degrees and 60.6 degrees for Co and Ni, respectively. In addition, the metal-azide-metal units form large M-N3-M torsion angles, which are magnetically important geometrical parameters, of 71.6 degrees for M=Co and 75.7 degrees for M=Ni. It should also be noted that the M-N-N angles associated with end-to-end azide group, another magnetically important structural parameter, fall into the experimentally observed range of 120-140 degrees as 128.3(3) and 147.8(3) degrees for cobalt species and 128.4(2) and 146.1(3) degrees for nickel species; these values deviate from the theoretical value of around 164 degrees at which the incidental orthogonality is achieved under the torsion angle of 0 degrees. The compounds 1a and 2a have unique magnetic properties of ferromagnetism, zero-field splitting, and spin canting. The MO calculations indicate that the quasiorthogonality between the magnetic orbitals of metal ions and the p atomic orbitals of the bridging azide is possible in the observed structures and leads to the ferromagnetism. The spin canting related to the perturbation of ferromagnetism arises from the magnetic anisotropy and antisymmetric interactions judged by the structural parameters of the zero-field splitting and the tilted MN4 planes in a chain. The enhancement of magnetic interactions was accomplished by dehydrating the chain compounds to afford two soft magnets with critical temperature T(C) and coercive field of 2 K and 35 G for 1b and 2.3 K and 20 G for 2b, respectively.

Ferromagnetic resonance studies of Ni nanowire arrays

Abstract: Using ferromagnetic resonance, the angular dependence of the uniform precession mode of infinite cylinders is investigated at room temperature for low density Ni nanowire arrays, embedded in a polycarbonate membrane, with wire diameters ranging from 35 mn to 500 nm. All wires reveal a very similar behavior of the resonance field vs angle, independent of the wire diameter and wire density, corresponding to the uniform precession mode of an infinite cylinder including the shape demagnetization anisotropy and a small uniaxial anisotropy contribution. From the analysis of the angular dependence of the linewidth, the distribution of the wire orientation and the effective anisotropy field can be estimated. The latter is broadened due to the presence of a sub-structure in the absorption spectra.

Ab initio calculation of the anisotropy effect of multiple bonds and the ring current effect of arenes—application in conformational and configurational analysis

Abstract: Substituents containing magnetically anisotropic chemical bonds, e.g. double bonds, triple bonds or the aromatic phenyl ring, influence the shielding of any nucleus in the molecule by their anisotropy effect dependent on its geometrical position. This effect of the magnetic anisotropy of neighbouring groups on the chemical shift of nuclei is usually specified qualitatively by the anisotropy cone. In this paper, the magnetic anisotropy effect of unsaturated chemical bonds and the ring current effect in arenes have been quantitatively calculated as nuclear independent chemical shieldings (NICSs) in a three dimensional grid of lattice points around the molecule using the GIAO method integrated into the GAUSSIAN 94 calculation program. Plotting the shielding/deshielding data thus obtained as iso-chemical-shielding surfaces (ICSS) around the magnetically anisotropic moieties allows us to quantify both direction and scale of the anisotropy effect. The calculation of the anisotropy effect of double and triple bonds, and the ring current effect of the phenyl ring, has been applied to a number of stereochemical problems; especially in conformational analysis this method proved very successful in quantitatively assigning 1H chemical shifts and hereby the stereochemistry of the molecules studied. In addition, contributions to 1H chemical shifts based on the anisotropy effect of neighbouring groups and based on other substituent effects could be differentiated quantitatively. Considerable deviations from the qualitative sketches of the anisotropy effects of double and triple bonds published in text books were found.

Importance of correlation effects on magnetic anisotropy in Fe and Ni

Abstract: We calculate magnetic anisotropy energy of Fe and Ni by taking into account the effects of strong electronic correlations, spin-orbit coupling, and noncollinearity of intra-atomic magnetization. The LDA+U method is used and its equivalence to dynamical mean-field theory in the static limit is emphasized. Both experimental magnitude of magnetic anisotropy energy and direction of magnetization are predicted correctly near U = 1.9 eV, J = 1.2 eV for Ni and U = 1.2 eV, J = 0.8 eV for Fe. Correlations modify the one-electron spectra which are now in better agreement with experiments.

Modification of Co/Pt multilayers by gallium irradiation—Part 1: The effect on structural and magnetic properties

Abstract: Atomic force microscopy, transmission electron microscopy, optical, and magneto-optical microscopy have been used to study how structural and magnetic properties are changed when a Co/Pt multilayer is quasihomogeneously irradiated with Ga ions. Under low irradiation fluence, both grain size and texture in the multilayer increase. These effects continue for fluences in excess of 1×1015 Ga ions/cm2, but beyond this dose significant thinning of the multilayer is also observed. Three distinct irradiation-induced magnetic regimes with sharp transitions between each were identified. For Ga fluences less than 5×1012 ions/cm2, the irradiated region retains perpendicular uniaxial anisotropy but with coercivity lower than that of the as-grown film. For fluences between 5×1012 and 1×1013 Ga ions/cm2, a transition from perpendicular to in-plane magnetization was experienced. Very little change of the in-plane magnetic properties of irradiated multilayers is then observed until the sample experiences a ferromagnetic t...

Co-Zr-O nano-granular thin films with improved high frequency soft magnetic properties

Abstract: A study was made of the properties and structure of Co-Zr-O nano-granular films prepared by rf reactive sputtering in an atmosphere of argon and oxygen gases. We found soft magnetic Co-Zr-O films in a wide compositional range near Co-ZrO/sub 2/ and investigated systematically the compositional dependence of their magnetic properties and electrical resistivity. The films near Co/sub 60/Zr/sub 10/O/sub 30/ simultaneously have anisotropy fields more than 150 Oe, coercivities less than 3 Oe, saturation magnetizations more than 9 kG, and electrical resistivities more than 1000 /spl mu//spl Omega/cm. The frequency response of permeability of these films is excellent. And they show a high resonance frequency exceeding 3 GHz.