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The giant magnetic-impedance (GMI) effect in FeCoSiB thin films was investigated. By introducing the role of demagnetizing field, based on linear Maxwell’s equations and Landau-Lifshitz-Gilbert (LLG) equation, the expressions of permeability and impedance were obtained and the theoretical model in this paper was significantly improved. A numerical simulation was conducted using MATLAB. For the thickness of thin film being close to the skin depth when the frequency of alternating current was up to megahertz, it could be found that the calculation results could match the experimental data very well when the thickness of the FeCoSiB thin film was greater than skin depth, while when the thin film thickness was less than skin depth, the calculation results had a big distortion. The influence of the demagnetization factor of FeCoSiB thin films on the GMI effect was also researched. This work was a tentative research on the simulation of the GMI effect of thin films. It might provide an attempt on the theoretical calculation of the GMI effect of thin films and guidance for the fabrication of thin-film GMI sensors.

Ru underlayer effects on the thermal stability of the magnetic properties in Co-Sm amorphous films have been investigated in terms of its robustness for the thermal-process in the fabrication of GHz band micro-magnetic devices. The anisotropy magnetic field Hk of the Co-Sm film was tending to decrease with an increase in the annealing temperature, but the reduction in Hk due to thermal-process became small by introducing the Ru underlayer. The high-resolution transmission electron microscopy (HR-TEM) observations revealed the presence of nanosized crystalline Sm segregation at the interface between the Co-Sm film and SiO2/Si substrate in the films without Ru underlayer, while there is no Sm segregation in the film with Ru underlayer. Sm segregation and the subsequent thermally induced phase-separation are one of the factors for the reduction in Hk. Ru underlayer effectively prevents the segregation of crystalline Sm and the resulting reduction in Hk. High-frequency magnetic property of Co-Sm film with Ru underlayer was superior to that without Ru underlayer for same annealing condition.

The magneto-impedance (MI) effect in RF sputtered (CoFe)/sub 80/B/sub 20/ zero-magnetostrictive amorphous films are presented. The relation between annealing conditions and MI characteristics was investigated. Impedance Z monotonously decreased with increasing applied field Hex when a high frequency sinusoidal current was applied to the sample annealed in a rotational field. In case of the samples having transverse anisotropy, Z sharply increases with Hex for the region Hex

Co-Fe-Si-B films have been prepared using a roll coater and DC magnetron sputtering system onto a polyethylene terephthalate substrate. This thin film exhibited an excellent uniaxial anisotropy introduced by an asymmetric thermal shrinkage of the substrate. Reversal with a single large Barkhausen pulse has been observed in thin film structure 1 mm by 50 mm by 0.65 /spl mu/m. Closure domains have been clearly identified at the film ends. The threshold for the reversal is the coercive force. The reason for reversal with a single Barkhausen jump is that the long narrow film geometry has essentially zero demagnetizing field over most of the film. Once the walls start to move through the center portion of the film, there is nothing to stop them so the reversal proceeds with a single large Barkhausen pulse.

The magnetic properties of amorphous films with the composition (Bi/sub 2/O/sub 3/)/sub 0.5-x/(Fe/sub 2/O/sub 3/)/sub 0.5/(CaO)/sub x/ are investigated. Samples with x=0-0.05 were prepared in a pure oxygen or mixed oxygen-argon atmosphere by the RF sputtering technique. As-sputtered films are X-ray amorphous and paramagnetic at room temperature. The films show a spontaneous magnetic moment when annealed in air at temperatures T/sub a/ above 400 degrees C. Data on the room temperature saturation induction 4 pi M with T/sub a/, followed by a maximum in 4 pi M for T/sub a/=600-700 degrees C, depending on the x-value. At higher T/sub a/, a decrease in 4 pi M is observed. The room temperature 4 pi M is found to decrease with increase in x, from 970 G for x=0.1 to 300 G for x=0.5. The Curie temperature is lower than the crystallization temperature. Ferromagnetic resonance studies show a uniaxial or planar anisotropy in the films. X-ray diffraction data do not indicate the precipitation of crystalline ferrimagnetic oxides in the annealed films and the observed magnetization is therefore attributed to ordered amorphous clusters. >

A new hybrid device composed of a magnetostrictive amorphous FeSiB film on piezoelectric PZT substrate is described. DC and AC electric fields were applied to the PZT substrate and the magnetic properties of the magnetostrictive film were observed. Both the initial permeability and the coercive field of the film changed drastically (about 300%) due to the inverse magnetostrictive effect when electric fields were applied. A possible application of this hybrid element is a voltage controlled variable inductor. >

It is shown experimentally that amorphous films of U-Sb and films with 20% Co and Mn added are all ferromagnetic with Curie temperatures as high as 135 K with magnetic moments per uranium of up to 1.4 mu /sub B/. Magnetooptical polar Faraday and Kerr rotations at 10 K and 40 kOe have values up to +2*10/sup 6/ degrees /cm and -3 degrees , respectively. The magnetooptical rotation correlates with Hall angles of up to 17 degrees . It is suggested that U-Sb magnetooptical effects and Hall effects are due to an intraband transition. >

Co-Fe-P and Co-Fe-Sn-P amorphous soft magnetic alloys have been developed by electroplating. These alloys have zero magnetorestrictive compositions and show a high saturation magnetic induction B/sub s/ of 10-13.5 kG and high permeability of 3000-5000 at 5 MHz with 2- mu m thickness. It was found that the addition of Sn to Co-Fe-P improves the corrosion resistance without decreasing saturation magnetic induction. The magnetic domain structures of the thin-film head-shaped cores with Co-Fe-P amorphous films were also observed by the magnetooptical longitudinal Kerr-effect technique. It was observed that the corrosion resistivity of Co-Fe-Sn-P amorphous alloy is superior to that of Co-Fe-P amorphous alloy. >

The domain wall dynamics in thermomagnetic recording of TbFeCo amorphous films is interpreted in terms of a model comprising magnetization reversal nucleation followed by a wall displacement process. The nucleation of the reversed domain from the saturated magnetization state occurs with a field usually observed as a nominal coercivity in Kerr or magnetization hysteresis loops. The concept of wall coercivity, which is often smaller than the nucleation field, is explicitly incorporated in the stability condition of the cylindrical domain during the wall displacement process. The model predicts both the recorded domain size and its dependence on recording power and applied field. >

Microstructures, optimum sputtering conditions, and annealing methods were investigated for the purpose of obtaining zero magnetostriction amorphous films with good magnetic softness. Sputtering conditions which suppress formation of columnar structure in films were studied, and films with high density were obtained. The mechanism of columnar structure suppression is discussed. Annealing in an ellipitically rotating field is effective to reduce in-plane anisotropy and Barkhausen-type noise, and to obtain very weak anisotropy for high initial permeability. Some of the samples thus obtained exhibit excellent softness with high initial permeability.

Properties of amorphous heavy rare earth-transition metal films are presented. Attention is concentrated on the properties which are important from the point of view of possible applications, namely: magnetic structure, perpendicular anisotropy, linear magnetostriction, and coercivlty as well as the spontaneous Hall effect. Possible applications of the films considered are shown, in particular, applications as the information storage media in digital memories, as well as in surface acoustic wave devices and in devices which utilize the Hall effect are examined.

A recent study on GdCo amorphous alloy films obtained by RF-sputtering onto glass substrates is reported. The susceptibility has been measured and from the field dependency of the susceptibility the anisotropy constant and the intrinsic stray field of the films have been calculated. In addition to the investigations at the film surface, the film-substrate interface has been investigated in the same way. The anisotropy and stray field at the film-substrate interface deviated strongly from the values at the opposite spot. As a result, the magnetization is expected to be inhomogeneous through the film, leading to ripple effects as known from soft magnetic films. In order to describe these effects, a micromagnetic ripple theory was developed, assuming a one-dimensional variation of the magnetization as well as of the local anisotropy.

Strong ferromagnet-like glasses have been prepared by rapidly quenching the molten mixture of antiferromagnetic BiFeO 3 and ZnFe 2 O 4 and by depositing simultaneously the ionized clusters of Bi, Zn and Fe atoms in a low pressure oxygen gas atmosphere. The Curie temperature of the glasses appears at 460-510 K and the magnetization reaches about 15-20 emu/g at 10 kOe at room temperature. Based on the Mossbauer effect and EXAFS measurements, the glass is concluded to be a speromagnet consisting of magnetic spins localized on each Fe atom tetrahedrally surrounded by four 0 atoms.

In this paper, magnetic properties of CoZr amorphous films prepared using low-energy ion-beam sputtering are investigated by varying the accelerator voltage and beam current of a single-grid ion-beam sputtering system. It is shown that CoZr films become amorphous with a lower Zr content when the films are prepared with lower accelerator voltage or lower ion-beam current. It is also clarified that the saturation magnetostriction constant of amorphous CoZr film becomes smaller as the Zr content becomes smaller ; a film with a Zr content of approximately 3.3at% has a magnetostriction constant of zero without adding a third element such as Nb, Ta or Re. CoZr amorphous films with a saturation magnetization of more than 1.5T, a coercive force of less than 0.2Oe and a magnetostriction constant of zero could be obtained using low-energy ion-beam sputtering with an accelerator voltage of less than 300V.

The magnetic and structural changes of amorphous films, which are prepared by DC diode sputtering on to liquid nitrogen-cooled substrates, during crystallization have been investigated. The targets are made of hard magnetic materials SmCo 5 , Sm 0.5 MM 0.5 Co. The study of crystallization process on the SmCo 5 amorphous films by X-ray and electron diffraction shows that the B-Co phase appears at 550°C, but it has only two B-Co diffraction fringes and the original amorphous wide band until 750°C, which shows that the crystalline phase of SmCo 5 intermatallic compound has not yet formed. It differs from the thick amorphous films as reported in the references. It is possible that the films have different crystallization process for larger surface energy. The measurements of the magnetic balance, vibrating sample magnetometer, Hall voltages and magnetic torque show that those amorphous films are soft magnetic and possess in-plane magnetic anisotropy. After the heat treatment of crystalline, the magnetizations have increased distinctly, but still have not hard magnetic property. It coincides the consequence of the structure study which has not formed the intermetallic compound.

In this paper, the optimum deposition conditions of amorphous Co-Zr films fabricated by ion beam sputtering and their magnetic properties are investigated. The amorphous state is achieved at a low Zr content ( near 5 - 10 at% ) and is dependent on the substrate temperature. Co-Zr alloy films with a Zr content of 4.5 at% become amorphous on a -130 °C substrate, whereas a Zr content of more than 6 at% is necessary to obtain amorphous films on a 40 °C substrate. The resistivity of the films increases monotonically with Zr content or as the substrate temperature decreases from +300 °C to -130 °C. It is shown that the addition of a small amount of Re to the films decreases magnetostriction, although it lowers saturation magnetization slightly. A magnetostriction value of less than 10-7is obtained when 2 to 3 at%Re is added to the Co-Zr films with a 6 to 8 at%Zr. Ion beam sputtered Co-6 at %Zr-2at% Re in 1 to 3 μm thick amorphous films exhibits the following excellent properties: a saturation magnetization of more than 13 kG, a permeability at 10 MHz of more than 5000, and a Vickers hardness of over 700.

To investigate the mechanism of perpendicular magnetic anisotropy K u in rare earth-transition metal amorphous films, K u was measured for (Gd 0.75 R 0.25 ) 19 Co 81 films with varying the rare earth element R. Results were analysed based on a single ion anisotropy model using a point charge approximation. The dependence of K u on rare earth element is well explained with the single ion anisotropy. A model was proposed in which anelastic deformation during deposition of the film is responsible for the induction of K u . Magnetostriction can also be explained with a point charge model with screening.

An extensive study of the magnetic and magneto-optical properties for Nd x Fe 100-x , Pr x Fe 100-x and Nd 40 - Fe 51 Co 6 Ti 3 amorphous films synthesized by r.f. sputtering onto heated substrates has been carried out. Both Nd-Fe and Pr-Fe alloy films exhibit the maximum values of the perpendicular magnetic anisotropy constant K u at 300K at about 40 at% of Nd and Pr elements. The strong thickness dependence of K u was found in both Nd 40 Fe 51 - Co 6 Ti 3 and Pr 40 Fe 60 films fabricated at the substrate deposition temperature T_{s}=210 \sim 250\deg C. The Kerr rotation angle θ K increases with decreasing wavelength in the range from 350 to 800 nm in those alloy films with Nd and Pr. This trend is in contrast to that of films with heavy rare earths. Together with observation by high resolution electron microscopy, it is proposed that a short range atomic ordering in a microcrystalline amorphous structure plays an important role in the perpendicular magnetic anisotropy mechanism.

Thermomagnetic writing utilizing temperature dependence of coercivity was proposed in magneto-optical recording as high density thin film memory. Rare earth-transition metal(RE-TM) amorphous films with perpendicular magnetization(GdFe,GdCo,TbFe etc.) were successfully prepared by sputtering or evaporation technique. Multi-source rf-sputtering method was used to prepare a uniform amorphous film. Uniformity of compensation temperature, Curie temperature and coercivity over a wide area was fairly good under the insertion of the window. Amorphous TbFeCo,GdFeBi and GdCoBi films have been studied to obtain a higher Kerr rotation angle that is important characteristic of magneto-optic recording media.

Perpendicularly magnetized amorphous Pr x Fe 100-x films were successfully fabricated by r.f. sputtering for 30\leq\times\leq60 . The dependence of the Curie temperature T c on Pr content is in accordance with that of the melt -spun samples, except for x larger than 50. The change in K u with temperature of Pr-Fe films is similar to that in Nd-Fe-Co, and there seems to be a transition in anisotropy mode from uniaxial to conical. The dependence of polar Kerr rotation angle θ k on wave length in Pr-Fe and Nd-Fe-Co films suggests a contribution of Nd and Pr to the magneto-optical effect.

It has been found that the perpendicular anisotropy Ku in amorphous Tb-Fe and Tb-Co films prepared by rf sputtering changes remarkably when H 2 gas is added to Ar sputtering gas. Ku in Tb-Fe films decreases with increasing H 2 partial pressure, while Ku in Tb-Co films increases and reaches almost 106erg/cm3. The internal stress in the films changes slightly with increasing H 2 partial pressure. Consequently, the change in Ku can not be explained in terms of magnetostriction. Mass spectroscopy shows that those films sputtered in H 2 -added Ar gas contain H 2 about three times more than those sputtered in pure Ar gas. It is likely that H 2 induces change in microstructure in films causing large change in Ku. However, the mechanism and the reason for different behaviors between Tb-Fe and Tb-Co are not clear yet.

Resputtering effect on the uniaxial magnetic anisotropy in amorphous GdCo films has been investigated. A sputtering apparatus has been constructed which is able to change the energy and the accommodation rate of the resputtering Ar ions independently of each other. The energy of Ar ions bombarding the substrate electrode or the film has been measured by means of a Faraday cup and has been found to be smaller than the bias voltage applied to the substrate electrode. The deposition rate of the film has been found to decrease linearly with an increase in the accommodation rate of the resputtering Ar ions. The product of the uniaxial anisotropy constant and the deposition rate has been found to be proportional to the accommodation rate of Ar ions with constant energy. This result agrees with the selective resputtering-induced anisotropy model.

The effect of annealing on the compensation temperature of Gd-Co and Gd-Fe thin films, which are prepared by rf-sputtering without dc bias fields at low temperatures (100-150°C), were studied. It is found that the changes of T comp in vacuum are faster than that in air. XPS studies showed that oxygen not only bonds preferentially to Gd atoms, but also reacts with the Co atoms (Fe atoms) in air annealing. The oxidation of Co atoms (Fe atoms) leads to a slow rate of change in T comp after annealing in air.

The results of some measurements of the magnetic properties of metastable, vapour quenched films of nickel, cobalt and their alloys are presented. The reduced magnetization of the films in their amorphous and crystalline states has been obtained as a function of temperature and estimates of the phase transformation temperatures and Curie temperatures have been made from the magnetic and some electrical resistance measurements. Changes in the magnetization of the crystalline phase are discussed in terms of theories of superpara-magnetism. Finally the magnetization of the amorphous state is discussed qualitatively in terms of previously obtained structural data for the single element films.

The relaxation process of induced anisotropy has been investigated in Co-Zr and Co-Ti sputtered films. For the analysis of the process, the films have been annealed isothermally in a static magnetic field after annealing in a rotating field. The relaxation curves have been fitted with calculated ones assuming the distribution of the activation energy. The mean values of the activation energy and their distribution have been estimated at (2.1±0.2)eV for Co 88 Zr 12 and (1.8±0.2)eV for Co 83 Ti 17 films, respectively. The relation between effective permeability and the uniaxial anisotropy can be well explained by the single domain theory.

The new sputtering technique was developed in which film deposition and ion bombardments were performed alternately and independently. By the technique, amorphous Gd-Co films were prepared with various thickness of the periodically deposited layers (t d ). It was confirmed that ion bombardments by applying the bias of -100 \sim-200 V change the composition within only about two atomic layers near the surface. The films with the compositional modulation of amplitude of a few at.% were synthesized in the range of t d larger than about 0.6 nm. A large anisotropy perpendicular to the film plane appeared abruptly at t d larger than 2.0 nm and the anisotropy decreased as t d increased. The results obtained may be interpreted qualitatively by the improved pair-ordering model.

The effect of resputtering on perpendicular magnetic anisotropy has been investigated for amorphous Gd-Co, Gd-Fe, Tb-Co and Tb-Fe films using a dual ion beam sputtering system. In Tb-Co and Tb-Fe films, perpendicular anisotropy increases remarkably owing to resputtering, while in Gd-Co and Gd-Fe films, it changes only through compositional change caused by resputtering. It is likely that the different behaviors between two cases are due to the fact that Tb is anisotropic and Gd is isotropic atom. However, its mechanism is not clear.

A systematic study of magnetooptical properties for four different varieties of the (Pr,Nd)-(Tb,Dy)-FeCo system, focusing on temperature and wavelength dependences of Kerr rotation theta /sub k/ for alloy films and multilayered films, was made. The same relation between Curie temperature T/sub c/ and theta /sub k/ at a 830-nm wavelength was obtained for (Pr,Nd)-(Tb,Dy)-FeCo and (Tb,Dy,GdTb)-FeCo alloy films where the Co to FeCo ratio was less than 20 at.%. It was found that in the range of 500 nm to 900 nm the absolute magnitude of theta /sub k/ for all quaternary systems was always less than that for Dy-FeCo. These results suggest that amorphous rare-earth-FeCo alloy films containing Nd or Pr are not superior to (Tb,Dy)-FeCo films in regard to recording sensitivity and recording density in magnetooptical disks. On the other hand, theta /sub k/ enhancement was observed for Nd-Dy-FeCo multilayered films. This theta /sub k/ enhancement is not caused by the addition of Nd, but is due to the effect of film microstructure on theta /sub k/. >

ZnO film coated Co-based (2705 X) amorphous ribbons are prepared by the successive ionic layer adsorption and reaction technique. The influence of coating on giant magneto-impedance (GMI) has been investigated over a frequency range from 0.1 to 3.5 MHz and under a static magnetic field between -8 and +8 kA/m. The highest GMI ratio of 15.63% was obtained in the coated Co-based amorphous ribbons which is 80% higher than the sample without coating. The results indicate that the surface coating process plays an important role in the GMI effect.

The processes to prepare amorphous CoFeNiNbSiB soft magnetic thin films using RF sputtering have been investigated systematically. It has been found that one can obtain soft magnetic films with good qualities at low argon pressure, 4 × 10-3torr. After annealing them in a rotating field, when the initial permeability of films can be raised above 3000 up to 10 MHz, the films show good frequency response. The structure relaxation processes of amorphous films during annealing have been studied by resistance monitoring method. It has been found that the amorphous films at high temperature experienced four obvious successive stages of relaxation.

Amorphous alloy films, mainly composed of Co-Nb, have been studied by radio frequency (RF) sputtering. These amorphous films having small magnetostriction show excellent soft magnetic properties after the magnetic annealing we have developed. One of them with the composition of (Co 83.5 Fe 2 ) 92/85.5 Nb 8 was found to have very high saturation magnetization B_{s} = 14300 (gauss). The effects of additives such as Zr to the alloys have been investigated and amorphous films having high crystallization temperature as well as high saturation magnetization were successfully obtained. These amorphous films show fairly good wear and corrosion resistance as well as excellent thermal stability of the magnetic properties.

Magnetic and thermal properties of the amorphous films of (Fe,Co) 100-x (Ta,W) x , ( 4\leq\times\leq30 ) deposited by a rf diode sputtering have been investigated. The amorphous films were obtained for Ta or W content 'X' above 14 at.%. The dependence of 4πMs on X of the deposited films was examined in detail. The change of crystal structure of the films from the crystalline phase to the amorphous one at X=14 at.% with increase in X leads to a drastical decrease in 4πMs of the Fe-Ta films. The dependence of 4πMs on X of the Fe-W films is similar to that of the Fe-Ta films. On the other hand, 4πMs of the Co-Ta films decreases gradually with increase in X, even if the crystal structure changes from the crystalline phase to the amorphous one. The maximum 4πMs and the minimum coercive force Hc of the amorphous Co-Ta films are 10 kG and 0.57 Oe, respectively. The crystallization temperatures of the amorphous Co-Ta films are above 800 K, being much higher than those of 3d-transition metal-metalloid amorphous alloys. They may be useful as a soft magnetic material with high thermal Stability.

A previously presented method which focuses on the static conditions in crystalline films is useful for confirming the domain configuration by minimizing the total free energy in the films. This method is also highly applicable to amorphous films. This paper indicates that a stiffness constant, anisotropy constant and wall type can be reasonably assumed in the same manner as in the crystalline case. Domain structure in amorphous films can be analyzed for a wide range of magnetic anisotropy field and thickness with respect to domain wall type. Therefore, this method is very convenient for designing film heads or MR heads using amorphous films capable of achieving high saturated flux density and high permeability.

Co 1-x (Ta,Zr)x ( 0.05\leq x \leq 0.16 ) amorphous films with zero magnetostriction have been deposited by rf sputtering and their magnetic properties and thermal stabilities have been investigated. The amorphous films with zero magnetostriction are obtained in the composition range of Co content as high as 95 at.%. Saturation magnetization 4&piMs at room temperature of 95 at.% and 85 at.% Co-Ta-Zr films is about 15 kG and 10 kG, respectively and varies in proportion to the Co content in the films. These amorphous films have low coercive force Hc of about 0.1 Oe. Crystallization temperature T x of these films decreases monotonically with an increase of Co content and the films with a Co content of 93 at.% have T x of about 460 °C. Hc of these films with Co content less than 92.4 at.% changes little by annealing at a temperature below 350 °C. However, large uniaxial magnetic anisotropy is induced in the films by the annealing in a static magnetic field at a temperature above 300°C and these Co-Ta-Zr amorphous films have large unstable induced magnetic anisotropy.

Co-Zr and Co-Ta amorphous films with soft magnetic properties have been deposited by double ion beam sputtering. And the dependence of their crystal structure and magnetic properties on preparation conditions, especially on the ion bombardment during deposition, has been investigated. The composition range of Co content where the amorphous films are obtained becomes wider as the energy of bombarding ions increases; the amorphous films are obtained in the range of Co content as high as 98 at.% for Co-Zr system and 94.3 at.% for Co-Ta system. The amorphous Co 98 Zr 2 and Co 94.3 Ta 5.7 films show saturation magnetization 4πMs at room temperature about 16 kG and 15 kG, respectively. These amorphous films have low coecive force Hc below 0.5 Oe. Effective permeability μ eff of the Co-Zr films increases with an increase of the temperature of annealing in rotating field and with an increase of the energy of bombarding ions;μ eff of 2500 is obtained for the films deposited with 120 eV ion beam bombardment by setting annealing temperature about 300°C. μ eff of the Co-Ta films decreases with an increase of the energy of bombarding ions;μ eff of 2500 and 5200 is obtained for the films deposited with 120 eV ion beam bombardment and for those deposited without it.

The magnetic properties of ferrimagnetic amorphous films (Gd-Co, Gd-Co-Au) with perpendicular anisotropy, coated with Permalloy films with the in-plane anisotropy, have been investigated. Coating with Permalloy film or transition metal films (Fe, Ni, Co) lowers the compensation temperature in the amorphous films about 5°C compared with that of single layer. Therefore, the coercive force of the amorphous film coated with a transition metal film differs from that of single layer. On the other hand, coating with rare-earth metal film (Gd) or non-magnetic film (Ag) does not cause a shift of the compensation temperature. The direction of nucleated stripe domains in the amorphous films of double layers is controlled by a low in-plane field (15 Oe).

CoPt, CoPd, FePt, and FePd alloy thin films are deposited on MgO(111) single-crystal substrates by using a radio-frequency magnetron sputtering system. The effects of magnetic material and substrate temperature on ordered phase formation are investigated. CoPt, FePt, and FePd epitaxial films with the close-packed plane parallel to the substrate surface are obtained at substrate temperatures ranging between room temperature (RT) and 600 °C. CoPd films grow epitaxially at temperatures higher than 200 °C, whereas CoPd amorphous films are formed below the temperature. Metastable L11 ordered phase formation is recognized for the CoPt films prepared at temperatures ranging between RT and 400 °C. As the temperature increases from RT to 300 °C, the order degree of L11 phase increases. With further increasing the temperature, the degree declines. The CoPt films formed above 500 °C are with A1 disordered structure. L10 ordered FePt and FePd films with the c-axis 55 ° canted from the perpendicular direction are obtained at 600 °C, whereas A1 disordered FePt and FePd films are formed below the temperature. No ordered phase is formed in CoPd film. The L11 ordered CoPt films show perpendicular magnetic anisotropies. As the order degree of L11 phase increases, perpendicular anisotropy is enhanced. On the contrary, the L10 ordered FePt and FePd films have in-plane anisotropies. The magnetic properties are influenced by the kind of ordered phase and the order degree.

The induced uniaxial anisotropy field in thin permalloy and CoZrNb films was investigated. The value of the induced anisotropy field H/sub k/ of permalloy films of 77-81 at%Ni concentration was found to decrease as the film thickness decreased below 20 nm, even after annealing procedure in a magnetic field. The value of H/sub k/ at 3 nm was found to be nearly half that at 20 nm. A series of CoZrNb amorphous films showed a qualitatively similar thickness dependence of N/sub k/. Moreover, a similar reduction of H/sub k/ was observed at 77 K. On the other hand, the easy axis of Ni/sub 79/Fe/sub 21/ films thinner than 20 nm was switched to the field direction by annealing with a magnetic field perpendicular to the easy axis of the as-deposited films, even at a low annealing temperature of 160/spl deg/C. The absolute value of H/sub k/ in the 3 nm film after annealing at 160/spl deg/C was nearly as large as in the as-deposited film. It is likely that the rearrangement of atom pairs can easily occur in the surface region, resulting in the switching of the easy axis to the annealing field direction in very thin films.

High-frequency permeability spectra of FeSiB coatings prepared with spark-eroded magnetic particles were studied. In order to measure the relative permeability of FeSiB coatings with low permeability more accurately, the calibration procedure of the existing permeameter was modified. The modified permeability spectra indicate that FeSiB coatings have the relative permeability below 10 and appreciable losses at frequencies above ~20 MHz. Permeability spectra of CoTaZr amorphous films with the relative permeability above 600 were used for the comparison

The dependence of Tb and Co concentration on the magnetoresistance (MR) of TbFeCo amorphous films with perpendicular magnetic anisotropy have been studied at room temperature. Tb/sub x/Fe/sub (88-x-y)/Co/sub y/ films (where x=15--37 at% and y=5--25 at%) with thickness of 200 nm are deposited by dc-magnetron sputtering. The MR ratio is sensitively dependent on the Tb concentration. The MR ratio is increased up to about 2.8% for a Tb concentration of about 22.4 at% then decreased for more Tb content. No significant effect of Co concentration on the MR ratio has been observed. The relation between MR ratio and film composition can be ascribed to the dependence of the domain wall width on the film concentration. The domain wall width decreases with an increase in Tb concentration and again increases for more Tb content showing its minimum value at about 22.4 at % of Tb concentration. It may be considered that the observed MR is contributed from the domain wall.

Etching of phase-change memory thin films is essential in the processing for the manufacture of devices. The Ge/sub 2/Sb/sub 2/Te/sub 5/ thin film as a typical material for such purposes can be control-etched by an aqueous solution of 20% nitric acids (HNO/sub 3/). It was found that the Ge/sub 2/Sb/sub 2/Te/sub 5/ films in amorphous state could be etched more uniformly than that in crystalline state. The etch rate can be well controlled to be 4.6 nm/s using such a solution, resulting in macroscopic and microscopic uniformity on amorphous films. It is therefore suggested that the crystallization annealing of Ge/sub 2/Sb/sub 2/Te/sub 5/ thin films should be done after a wet etching process in the manufacture of phase-change random access memories.

Summary form only given In order to advance micro-machines such as small motors in mobile phones, Nd-Fe-B films with the thickness of several tens of microns are strongly needed. Although a sputtering method is convenient to obtain film magnets, we have difficulty in realizing a high deposition rate. In this contribution, we succeeded the high deposition rate of 50 /spl mu/m/h using the laser ablation technique. Suppression of oxidation of a key point to obtain Nd-Fe-B film magnets with high coercivity, therefore we used the following methods. (1) Ta substrates and a Ti sublimation pump used as an auxiliary pump were used during deposition. (2) The composition of a target was set to Nd2.6Fe14B which included a larger amount of Nd compared with the stoichiometric composition of Nd2Fe14B. hi addition, the distance between a target and a substrate was set at approximately 5mm to realize a high deposition rate. One-hour-deposition using laser ablation technique enabled us to obtain Nd-Fe-B amorphous films with the thickness of approximately 50 microns. The authors show the coercivity of Nd-Fe-B films as a function of annealing time t/sub a/ at the temperatures of 823, 923 and 1023 K. The annealing time ta indicates the time after the temperature reached a preset temperature. We obtain the H/sub c/ value lager than 800 kA/m for t/sub a/ = 0 at 923 K. This value was the highest one through our experiments. They also show the hysteresis loop of a sample fabricated under the same condition. It was clarified that approximately 50 micron-thick Nd-Fe-B film magnets with the H/sub c/ value of more than 800A/m, I/sub r/ of approximately 0.6 T and (BH)/sub max/ of 56 kJ/m/sup 3/ can be obtained.

We have investigated ultrahigh frequency magnetic properties of amorphous Co-Fe-Zr-B alloy films deposited on glass substrates by dc magnetron sputtering. Microstructural characterization carried out on these films shows the amorphous nature of the films. The Co-Fe-Zr-B film with a thickness of /spl sim/2300 A exhibits excellent soft magnetic properties in the as-deposited condition, e.g., easy axis coercivity (H/sub c/) of /spl sim/1.5 Oe and 4 /spl pi/Ms of /spl sim/8.4 kG. The in-plane uniaxial anisotropy field (H/sub k/) is as high as /spl sim/28 Oe. This large anisotropy field significantly enhances the ferromagnetic resonance frequency (f/sub res/) to /spl sim/1.86 GHz. The relative permeability /spl mu/' of this film is shown to be /spl sim/200 and to stay nearly constant in the frequency range of 0.1 GHz-0.75 GHz. The full width at half maximum (/spl Delta/f) for the peak in the imaginary part of the permeability at resonance is /spl sim/0.35 GHz. It Is also found that the soft magnetic properties as well as the ultrahigh frequency properties of amorphous films have a strong dependence on film thickness. This is attributed to the change in the microstructure of films, which is closely related to the film growth conditions.

The magnetic properties of Fe-based amorphous films are thought to be highly sensitive to strain due to the large saturation magnetostriction and soft magnetic properties exhibited by the films. This is why patterned FeCoSiB films exhibit a large variation in their high-frequency impedance when strain is applied. To increase the sensitivity of strain sensors, it is very important to control the magnitude of magnetic anisotropy. We propose a method to control the magnetic anisotropy by stress bias annealing. By applying stress during annealing, we were able to control the anisotropy along the width of the patterned film. A strain sensor using a transverse-anisotropy-induced film pattern exhibited a figure of merit F/spl ap/8300, while a sensor without anisotropy exhibited F of only 500.

High moment FeRhN nanocrystalline films were laminated by Co/sub 90/Zr/sub 9/Cr (CZC) amorphous films, in order to improve the anisotropy definition and high frequency permeability. The experimental results also showed improved soft magnetic properties, higher resistivity, and better magnetic properties on sloped surfaces.

Thin films of the amorphous ternary alloy CoZrGd are deposited by single target magnetron RF sputtering. The Hall effect was studied as a function of Gd percentage. The amorphous films show unusually large spontaneous Hall effect, whose sign is strongly dependent on the film composition, as explained by the model of McGuire et al. Also, the films display perpendicular easy axis anisotropy, which significantly reduces the field needed to obtain technical saturation of the spontaneous Hall effect. Thus the sensitivity of the films can be substantially increased. The highest magnetic field sensitivity (-14.8%/Tesla) is accomplished with Hall angle (/spl rho/H//spl rho/) of -2.07% at a saturation field of 0.14 Tesla. This film has potential application in small fields.

Highly resistive (CoFeB)-(SiO/sub 2/) amorphous films were deposited on glass substrates and polyimide sheets by synchronous dual-rf magnetron sputtering. SiO/sub 2/ volume fraction dependence of magnetic properties and resistivity was investigated. The as-deposited films for SiO/sub 2/ volume fraction /spl upsi/=20 vol.% had low coercivities of H/sub c/=0.2-0.3 Oe, together with high resistivities of 1500-2200 /spl mu/ /spl Omega/ cm. The film exhibited an anisotropy field 40 Oe, a relative permeability of 200 and a saturation magnetization of 7.3 kG. The core loss of the films was 1-1.5 J/m/sup 3/ at 1 MHz for maximum flux density B/sub m/=0.1 T. The loss was found to be as low as those of Co-based ultra-thin ribbons. The films are useful as thin film cores in the micromagnetic elements which work in the MHz range.

The crystallization process of the Ag or Cu doped Sb/sub 2/Te/sub 3/ amorphous film was investigated by isothermal treatment for one hour at 100/spl deg/C, 200/spl deg/C and 300/spl deg/C respectively. The crystallization temperatures of Ag/sub 8.3/Sb/sub 34.9/Te/sub 56.8/ and Cu/sub 8.4/Sb/sub 35.1/Te/sub 56.5/ films determined by DSC analysis were more than 125/spl deg/C and 120/spl deg/C respectively, while that of the undoped Sb/sub 2/Te/sub 3/ film was 97/spl deg/C. It indicates that doping Ag or Cu can improve the room temperature stability of Sb/sub 2/Te/sub 3/ amorphous films. For pure and some Ag, Cu doped Sb/sub 2/Te/sub 3/ films, phase transformations from lower temperature metastable phases to higher temperature thermodynamic stable phases were found. This kind of phase transformation would cause the appearance of ambiguous exothermic peak in DSC curve. When the Ag content is increased to about 6.6 at%, the melting temperature of the film is enhanced from 415/spl deg/C for undoped film to higher than 450/spl deg/C. For the Cu doped film, same tendency can be achieved as Cu content is increased to 8.4 at%. The contrast ratios between as-deposited and 300/spl deg/C annealed films of Ag/sub 3.2/Sb/sub 35.8/Te/sub 61.0/ and Cu/sub 41/Sb/sub 37.4/Te/sub 58.5/ films were more than 42% and 37% respectively.

Fe/sub x/Ge/sub 100-x/ films with compositions in the range 50/spl les/x/spl les/82 at 300 K were deposited by rf diode, sequential sputtering from elemental targets. All the films were amorphous at 300 K indicating that the Fe concentration in the stable amorphous films was increased by more than 10 at. % over that obtained by vapor deposition. The sequentially sputtered Fe-Ge films exhibited a heteroamorphous morphology with nanoscale features that varied with composition. The variations in the 4/spl pi/M/sub s/ and T/sub c/ for the sputtered Fe rich films, agreed well with data extrapolated from measurements on Ge rich evaporated films. The improvement in the soft magnetic properties produced in these films by rotating magnetic field annealing (RFA) was shown to be correlated with changes in film morphology.

A simple processing method has been developed for studying model Nd-Fe-B magnets. The grain structure of these samples is comparable to that of melt-spun magnets. The samples are prepared by depositing films on a carbon foil TEM grid by laser ablation. The influence of temperature on the grain structure is emphasized. Deposition at room temperature yields amorphous films. Crystallinity is obtained at substrate temperatures above 600/spl deg/C during deposition. The size of the grains is about 20 nm.