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The temperature dependence of the extraordinary Nernst-Ettingshausen coefficient Q s ( T ) and of the electrical resistivity ϱ( T ) of amorphous ferromagnetic Metglas alloys 2605SC, 2714A and 2826MB were studied. The experimental data of Q s were examined using the formula proposed by Kondorskii and Berger: Q s = - T ( α + βϱ ). It was found that the Q s ( T ) dependence can be explained by phonon and spin disorder scattering. The latter plays the vital role.

The GMR effect of the [(Ni83Fe17=Py)/Cu]x100 multilayers (Mls) obtained by d. c. face-to-face sputtering technique deposited onto Si wafers were studied at room temperature (R. T.) and at 4.2 K. The GMR(dCu) oscillatory behaviour as well as the width of the first and the second AF coupling ranges have been found to be strongly affected not only by the presence of the superparamagnetic entities located at the Py/Cu interfaces but mainly by the existence of the magnetic bridges between Py sublayers. Zero-field-cooled and field-cooled magnetisation measurements confirmed the existence of the paramagnetic/superparamagnetic areas (at R. T.) for Py thicknesses up to 2.5 nm. The effectiveness of the magnetic bridges between Py sublayers has been found to be temperature dependent, leading to the temperature dependence of the remnant to saturation magnetisation ratio.

The magnetisation reversal of polycrystalline permalloy/copper multilayers with antiferromagnetic couplingwas measured as a function of temperature. The magnetisation behavior is discussed in the relation to the exstence of ferromagnetic pinholes bridging neighbouring permalloy layers.

A systematic investigation is made of the electrical resistivity of non-magnetic thin amorphous films, Fe1−xTix, in a wide range of the Ti concentration from x = 0.40 up to x = 0.87. An anomaly in electron transport phenomena is found in the vicinity of x = 0.75. For 0.68 < x < 0.83, the temperature dependences of resistivity are found to be proportional to lnT. In this range of x values a minimum of resistivity is observed. Es werden die Ergebnisse einer systematischen Untersuchung des elektrischen Widerstandes nichtmagnetischer dunner amorpher Fe1−xTix Schichten in einem weitem Ti-Konzentrationsbereich von x = 0,40 bis 0,87 dargestellt. Es wird eine Elektronentransportanomalie in der Nahe von x = 0,75 gefunden. Fur 0,68 < x < 0,83 ist die Temperaturabhangigkeit proportional zu lnT. In diesem Intervall von x-Werten wird ein Widerstandsminimum beobachtet.

Magnetoresistivity depending in an oscillatory way on d Ag has been found in wedged Co( d Co )/Ag( d Ag ) discontinuous multilayers. Two distinct maxima for d Ag = 1.1 and 2 nm have been observed. Simultaneously, a maximum in magnetoresistivity has been found for 80% Ag volume fraction. A decrease in the width of the magnetoresistance curves versus applied field was observed after annealing.

The correlation between magnetostatic or Neel's coupling and roughness of interfaces in sputtered Cu/Py/V/Py/MnIr/Cu multilayers was investigated with the help of atomic force microscopy and magnetometry. It is shown that the coupling strongly depends on the roughness of seed Cu layer which in turn depends on sputtering power. Roughness levels off after deposition of consecutive layers to about 0.2 nm rms.

The (Ni(80)Fe(20i)Col);CuAgAu/Co2 asymmetric sandwiches have been examined for different sublayer thicknesses. Magnetoresistance, magnetooptical Kerr effect and alternating gradient magnetometry measurements showed that for 1.2 nm less than or equal to d(CuAgAu) less than or equal to 1.6 nm our trilayers are antiferromagneticatly coupled whereas for d(CuAgAu) greater than or equal to 1.9 nm the coupling between Ni80Fe20i Col and Co2 is ferromagnetic. The ferromagnetic coupling strength oscillates with CuAgAu thickness with a period of 1 nm. The appearance of the ferromagnetic interlayer coupling for d(CuAgAu) greater than or equal to 1.9 nm and its oscillatory character result from the interplay between RKKY-Iike exchange coupling and the magnetostatic orange-peel coupling. The values of the ferromagnetic coupling field between Ni80Fe20iCoI and Co2 for a constant CuAgAu thickness can be either enhanced or reduced depending on the ratio between Col, Co2 and Ni80Fe20 thicknesses. In spite of oscillatory ferromagnetic coupling strength for d(CuAgAu) greater than or equal to 1.9 nm our trilayers show the GMR amplitude of about 10% and the GMR field sensitivity of about 5%/Oe at room temperature being very promising from the application point of view. (C) 2003 Elsevier B.V. All rights reserved.

The magnetoresistance and magnetic properties of Py/Co1/CuAgAu/Co2 have been examined. The fairly large GMR amplitude accompanied by high GMR sensitivity of about 5%/Oe was achieved. It has been shown that such high values of parameters characterizing the GMR effect could only be obtained due to the balancing effect between RKKY-like exchange coupling and magnetostatic coupling.

The magnetoresistive properties of [NiFe/CuAgAu/Co/CuAgAu] N multilayers are described. It is shown that these structures exhibit large resistance changes within a small magnetic field range. It leads to high GMR field sensitivities reaching 6.8%/Oe at room temperature. Magnetoresistance effect is anisotropic with the highest resistance changes being observed for field applied parallel to an easy axis of permalloy layers.

The magnetoresistive properties of sputtered [NiFe/Cu0.85Ag0.1Au0.05/Co/Cu0.85Ag0.1Au0.05](N) multilayers are reported. It is shown that these structures exhibit large resistance changes within small magnetic field ranges resulting in sensitivities of up to 6.8%/Oe at room temperature, The observed magnetoresistance effect is anisotropic. The largest resistance changes have been observed for magnetic fields applied parallelly to the easy axis of permalloy layers, (C) 2002 Elsevier Science B.V. All rights reserved.

The Co(25 nm)/Al(d(Al))-O-x/Ni80Fe20(25 nm), trilayers, with a Al thickness variation of 0.5 nm less than or equal to d(Al) less than or equal to 5 nm, were evaporated in ultra-high vacuum onto oxidised Si wafers. The simultaneous measurements of the magnetic hysteresis loops and thickness-dependent electric conductance were performed in-situ during deposition process. They were supplemented with surface topography and cross section images by atomic force microscopy and high-resolution transmission electron microscopy, respectively. We have shown that for an Al thickness of about 1.2 nm a transition from strongly ferromagnetically coupled Co and Ni80Fe20 characterised with single hysteresis loops to well separated magnetisation loops evident for weakly coupled layers occurs, The conductance measurements performed during deposition process as well as during 24 h oxidation process of the Al layer led us to the conclusion that independently on Al thickness nominally only 0.5 nm thick Al layer is oxidised. The influence of different buffer layers (Cy Au) on magnetisation reversal characteristics is also shown. (C) 2000 Elsevier Science B.V. All rights reserved.

In this contribution the in-situ conductance vs. deposition time dependences of Fe/Si multilayers are analysed. The plot of resistance multiplied by the square of the thickness as a function of iron thickness shows, that during the iron deposition initially amorphous-like Fe-Si mixture is formed, next the mixture crystallises, and finally bcc-Fe phase appears. The interface mixing is also manifested by the reduction of the total multilayer thickness measured by Small Angle X-Ray Diffraction.

This work presents the magnetic and electric investigation of Co-Pd thin films. It has been found that Co-Pd films obtained by the cosputtering method exhibit uniaxial anisotropy with the easy axis parallel to the plane of the film. The internal stress measurements showed the existence of the compressive stresses anisotropic in character.

The dependence of the giant magnetoresistance effect (GMR) on the interface structure in Fe/Cr multilayers was studied by magnetoresistivity and Mossbauer spectroscopy. The Fe/Cr multilayers consisting of Fe(6 nm) + [Cr(1.1 nm)/Fe(3 nm)](60) + Cr(1.1 nm) were deposited by dc magnetron sputtering. Samples were annealed for 1 h at temperatures ranging from 200 to 500 degrees C. The interface structure was characterized by conversion electron Mossbauer spectroscopy (CEMS). Various different Fe sites: the bulk, step and perfect interface positions were identified. The evolution of the fraction of Fe atoms in different environments vs annealing temperature revealed that annealing at 300 degrees C induces bulk and in-plane diffusion of atoms. Higher annealing temperature causes substantial roughening of the interface related to a strong bulk diffusion of atoms. Microstructural changes observed in the CEMS spectra correspond well to the GMR measurements which reveal an enhancement of magnetoresistivity in Fe/Cr multilayers annealed at about 300 degrees C and its decrease due to deterioration of the interface at higher annealing temperatures. (C) 1999 American Institute of Physics. [S0021-8979(99)19608-7].

Thermally evaporated (permalloy Ni80Fe20)/Cu multilayers were deposited on to quartz glass substrate, oxidised Si and etched Si wafers at room temperature and at 100 K. The samples were examined during an evaporation process by means of in situ conductance measurements whereas magnetisation, X-ray diffraction, atomic force microscopy and the cross-section electron transmission microscopy were performed ex situ to characterise our samples. Only a very small GMR effect was observed for samples deposited at RT and at 100 K. An absence of the antiferromagnetic coupling seems to result from the large interface roughness. Multilayers deposited at 100 K showed the existence of a highly topological disordered alloy-like structure formed during the deposition process. (C) 1998 Elsevier Science B.V. All rights reserved.

Thermally evaporated permalloy/copper (Py/Cu) multilayers were deposited onto quarts glass substrate, oxidised and etched Si wafers at room temperature and at 100 K. The samples were examined during an evaporation process by means of in-situ conductance measurements whereas magnetisation, A-my diffraction, atomic force microscopy and the cross section electron transmission microscopy were performed exsitu to characterise our samples. Only very small GMR effect was observed for samples deposited at R.T. and at 100 K. An absence of the antiferromagnetic coupling seems to result from the large interface roughness. Multilayers deposited at 100 A showed the existence of highly topological disordered alloy-like structure formed during deposition process. Introduction In contrast to sputtered (Ni80Fe20=Py)/Cu multilayers (MIs) [1,2] no GMR oscillatory behaviour has been noticed for evaporated samples as a function of Cu sublayer thickness [3]. The GMR effect for evaporated Py/Cu Mis was only observed in a post annealing state [3] whereas annealing of the sputtered Py/Cu Mis even at low temperatures can led to gradual degradation of the Interlayer coupling as well as of the GMR effect [2]. This strongly indicates the influence of the deposition technique on the interlayer coupling and on the chin effect in Py/Cu multilayers. In this contribution we present reasons why far evaporated Py/Cu multilayers no GMR effect is observed. We compare the morphology, surface topography and crystal structure of Py/Cu Mis deposited by evaporation at room temperature (R.T.) and at 100 K. Experimental The [Ni80Fe20/Cu](N) (N denotes a number of bilayers and N less than or equal to 30) Mts were evaporated in UHV system from Al2O3 crucibles onto different substrates (etched Si, oxidised Si wafers and a quarts glass) covered with Py or Cu buffer layers or without any buffer layer. Thickness of evaporated layers were controlled by a quartz micro-balance. The residual pressure in the vacuum chamber with liquid nitrogen baffle was 0.06 mPa. The deposition rate for both Py and Cu evaporated materials was about 0.01 nm/sec and the distance between crucibles and substrate holder was 50 cm. Thicknesses of Py (d(Py)) and Cu (d(Cu)) sublayers were changed in the range of 0.8 less than or equal to d(Py)(d(Cu))less than or equal to 2.5 nm. The surface topography and the crystal structure of the samples were examined ex-situ by atomic force microscopy (AFM), low-(LAXRD) and high angle X-ray diffraction (HAXRD) using Cu K-alpha radiation. The morphology of selected samples has been examined by means of the transmission electron microscopy of cross-section (TEM-CS). Conductance of the samples and their magnetoresistance were measured insitu during the deposition process with a pseudo-four point method. The magnetic properties of selected samples have been measured ex-situ at room temperature with a vibrating sample magnetometer (VSM) in-plane (i-p) and out-of-plane (o-p). Results and Discussion.

Using the thermal treatment for adjusting the giant magnetoresistivity (GMR) values in Fe(3 nm)/Cr(1.1 nm) multilayers, the temperature dependencies of resistivity and magnetoresistivity were examined. A reduction of the residual resistivities after the annealing processes at annealing temperatures lower than 300 degrees C was observed and simultaneously an increase of the magnetoresistivity was noted. Further annealing at higher temperatures degraded gradually the magnetoresistivity. Transport properties were found to be affected by two scattering mechanisms: electron-magnon scattering was dominant for the multilayers exhibiting higher GMR whereas electron-phonon scattering was more pronounced in samples with lower GMR.

Giant magnetoresistance effects and their field dependence in Fe/Cr multilayer films prepared by rf magnetron sputtering have been modelled using the concept of the existence of paramagnetic regions at the Fe/Cr interfaces. The model has been applied to as-deposited and annealed samples with the result that the approximate sizes of superparamagnetic entities at the interfaces (or their magnetic moment) could be determined. The variation of the magnetoresistivity was studied as a function of annealing temperature. It has been demonstrated experimentally that the magnetoresistance follows the square of the magnetisation dependence for Fe/Cr multilayers.

A strong correlation between the spontaneous Hall coefficient and GMR as a function of annealing temperature was found for Fe/Cr multilayers. The discrepancy between the effective magnetisation extracted from the Hall effect and the saturation magnetisation obtained from Faraday balance measurements was ascribed to the interface magnetic anisotropy.

ECDLs are of interest for direct overwriting (DOW) and super resolution in magneto-optic recording. A new approach is the use of RE/TM multilayer stacks as a basic film material which gives additional parameters to optimize magnetic properties. In a face to face dc sputtering equipment we produced multilayered films with a total thickness of 2000 A having sublayers of 10 A Fe and 4.5 to 15 A Tb. The actual net concentrations of the multilayers were determined using XRF. X-ray diffraction produced an amorphous halo, whereas small angle X-ray diffraction showed still the modulation wavelength of the multilayer. Double layers consisting of two multilayer stacks showed a characteristic magnetization reversal which can be explained by an exchange coupling with a comparatively high coupling energy σ w between the two stacks.

Formation of an amorphous phase in multilayered Ni Zr films has been studied on the basis of resistivity measurements. The obtained dependencies of resistivity on the wavelength of modulation for as-deposited films as well as on time, under isothermal annealing, have been shown to be well described by a planar model of film growth.

In multilayered thin films consisting of permalloy (Ni 80 Fe 20 ) and copper, a strong antiferromagnetic coupling and a related giant magnetoresistance can be found which oscillates with the thickness of the copper spacer layers. This, however, is usually detected only in sputtered films, whereas evaporated multilayers often show no or only a very weak coupling and giant magnetoresistance. Here, we report on a comparative study of sputtered and evaporated multilayers. In the first maximum of the antiferromagnetic coupling, i.e. at a copper thickness of 0.9nm. our sputtered films exhibit a saturation field of up to 0.1 T, a giant magnetoresistance of up to 25% and a pronounced magnetic superstructure peak in spin polarized neutron reflection. In contrast to this, the corresponding evaporated multilayers with nominally the same film thicknesses do not show any sign of antiferromagnetic coupling although measurements of the film resistance which were performed in situ, i.e. during the evaporation give evidence both for a smooth growth of the films as well as for the absence of interdiffusion effects. A subsequent analysis of the films by grazing incidence x-ray reflection, however, indicates a good and a poor multilayered structure for the sputtered and evaporated films, respectively, which could be due either to interdiffusion and/or to interface roughness. Additional atomic force imaging of the surface of the films point to an increased roughness caused by a more pronounced grain growth in the case of the evaporated films as a possible reason for the striking difference in the properties. Thus we conclude, that the absence of the antiferromagnetic coupling and giant magnetoresistance in the evaporated films should be related to an increased roughness and not to interdiffusion.

The result are given of the Curie temperature measurements for amorphous Fe1−xSix thin films as well as of the temperatures of crystallization. In order to explain the observed anomalies in transport properties a model is proposed assuming separation of the amorphous phases near the Si concentration x = 0.40. Assuming the existence of two amorphous phases of different conductivity for Si concentration close to x = 0.40, the increase in resistivity as well as the change in the sign and value of thermoelectric power are explained. Es werden die Curie-Temperaturen und die Kristallisationstemperaturen amorpher dunner Fe1−xSix-Schichten bestimmt. In der Nahe von x = 0,40 beobachtet man eine Anomalie in den Transporteigenschaften. Fur die Erklarung dieser Anomalie wird ein Phasensegregationsmodel vorgeschlagen. Die Annahme des Auftretens zweier amorpher Phasen in der Nahe dieses Si-Gehaltes erklart den Widerstandsanstieg sowie die Anderung des Wertes und Vorzeichens der Thermospannung.

DC resistivity ϱ and spontaneous Hall coefficient Rs, are measured in Fe1−xSix for 0.14 ≦ x ≦ 0.71 amorphous films produced by DC cosputtering. The behaviour of these parameters as well as saturation magnetization 4πMs upon annealing, and their composition dependences are discussed. The particular significance of a silicon concentration of x ≈ 0.40 is proved by the observations of a rapid increase of the electric resistivity ϱ(x), maximum values of Rs and 4πMs, and the semi-conducting character of the electric conductivity of this concentration (found to occur up to x = = 0.71). Es wird der Einflus der Warmebehandlung auf den elektrischen Widerstand ϱ, auf den spontanen Hallkoeffizient Rs und auf die Magnetisierung 4πMs amorpher Fe1−xSix-Schichten untersucht. Die Schichten werden mit dem Gleichstromspotterverfahren hergestellt. Es wird gefunden, das die elektrische Leitfahigkeit dieser Schichteu im Interval 0,14 ≦ x ≦ 0,71 einen Halbleitercharakter hat. Rs und 4πMs erreichen ihren maximalen Wert fur x ≈ 0,40. Fur diese Si-Konzentration erfolgt auch ein steiler Anstieg des Widerstandes.

Saturation magnetization and its temperature dependence of amorphous Nd 12 Co 82 B 6 thin films have been studied. The films were prepared by flash evaporation technique onto glass substrates cooled with liquid nitrogen. The Hall resistivity versus magnetic induction curves, ϱ H ( B ), were used for determining the saturation magnetization, M s , and the spontaneous Hall coefficient, R s , in the temperature range from room temperature up to about 700 K. Some non-monotonous behaviours ascribed to structural thermal processes, as well as a strong decrease in M s near the Curie point for amorphous alloy followed by another increase above T Ca due to the onset of crystallization were observed over that temperature range.

We report on giant magnetoresistance (GMR) of Si(100)/Cu-20nm/(Py-d Py /Cu-d Cu ) 100 where Py=Ni 83 Fe 17 , multilayer films prepared by face-to-face sputtering with 0.5≤d Cu ≤3.5 nm and 0.5≤ d Py ≤10 nm. It has been shown that the GMR sensitivity depends on the relative changes of resistivity as well as on the value of the antiferromagnetic interlayer exchange coupling strength J AF . The highest GMR sensitivity (0.5%/Oe) has been achieved for d Cu =2.1 nm and d Py =3.5 nm.