bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical recording in amorphous silicon films
Authors: Janai M. , Moser F.
Published: February 2003

The amorphous to polycrystalline transition in thin silicon layers is accompanied by a large change in optical transmission in the visible. By inducing this transition by laser annealing, high-resolution optical recording and visible-light readout have been demonstrated. As an optical recording material, amorphous silicon layers offer characteristics of high information-storage density, long-term stability, and negligible degradation upon repeated readout. Such an optical image in a thin silicon layer can be converted to a relief pattern by taking advantage of the difference in etch rate between amorphous and polycrystalline silicon, thus providing a method of producing patterns in silicon layers without use of intermediate photo-resist steps.
Source size line broadening in convex curved crystal x-ray spectrographs
Authors: Gersten M. , Rauch J. E.
Published: February 2003

Ray tracing techniques are used to derive an analytic approximation for the resolving power, λ/Δλ, of convex curved crystal spectrographs as a function of the linear source size parallel to the plane of dispersion and as a function of the Bragg angle. Using the derived expression, we investigate source size broadening in spectra from spatially and temporally integrated imploding-wire plasmas. We also compare the level spacing between the last discrete spectral line and the spectral line succeeding it to various line broadening processes: line broadening due to the finite size of the plasma source (source size line broadening), Doppler broadening, and line broadening due to the crystal rocking curve. We show that, in some cases, source size line broadening is comparable to the level spacing. Source size line broadening causes difficulties in obtaining the ion density from the series merging technique, since the latter is based on Stark broadening. We show that in some previously reported experiments the ion densities determined from the series merging technique should be considered an upper limit.
Heavy ion implantation in diamond
Authors: Teicher M. , Beserman R.
Published: February 2003

Antimony and nitrogen have been implanted at room temperature in type Ia diamonds. From the EPR spectrum we can deduce that for small implantation doses isolated broken bonds are created. Multiple defects are created for implantation doses D(Sb) = 2–5×1013 ions/cm2 and D(N) = 5×1014 ions/cm2. For higher implantation doses single broken bonds prevail. Complete graphitization is obtained for high doses: D(Sb)⩾5×1015 ions/cm2 and D(N)⩾1016 ions/cm2. In antimony doped diamonds the conductivity is only due to defects.
Precipitation as the phenomenon responsible for the electrically inactive phosphorus in silicon
Authors: Nobili D. , Armigliato A. , Finnetti M. , Solmi S.
Published: February 2003

The physical nature of the electrically inactive phosphorus in silicon was investigated by annealing experiments performed on laser annealed specimens doped by ion implantation up to 5×1021 at/cm3. The hypothesis of point defects, which compensate or make the excess dopant electrically inactive, is contradicted by the experimental results. It was verified that phosphorus solubility corresponds to the electrically active concentration in equilibrium with the inactive dopant, and that the latter is precipitated phase. This was confirmed by transmission electron microscopy (TEM) examinations with the weak beam technique, which detected a high density of very small coherent precipitates. This method allowed us to observe particles of the same kind even on specimens thermally predeposited in conditions typical of device technology. In both cases the amount of precipitates was consistent with the inactive dopant concentration. In addition these experiments show that precipitation is associated with a high enhancement of the diffusivity of the dopant. This phenomenon can account for the plateau region of the carrier profiles after thermal predeposition.
Between carrier distributions and dopant atomic distribution in beveled silicon substrates
Authors: Hu S. M.
Published: February 2003

In specimens beveled for spreading resistance measurements or copper staining, the ’’on-bevel’’ carrier distributions may be distorted from the correspondng dopant atomic distributions. The problem becomes very serious for very shallow structures in the 0.1–0.2 μm range. We have studied this problem by solving the two-dimensional Poisson equation for some 130 cases comprising several parameters. It is found that insofar as the deviation of the on-bevel electrical junction from the metallurgical junction is concerned, dopant profiles generally fall into two groups. Group I profiles exhibit significantly shallower on-bevel electrical junctions than corresponding metallurgical junctions, and the situation gets precipitously worse when junctions get shallower than 0.2 μm. Profiles in this group possess gentle tails, and include gaussian, complementary error function, and exponential profiles. Group II profiles exhibit a very small ’’positive deviation’’ of the on-bevel electrical junction from the metallurgical junction, and this deviation remains essentially unchanged as the metallurgical junction gets shallower. Profiles in this group have nearly linear or superlinear gradients in the vicinity of the metallurgical junction; a high concentration diffused arsenic emitter is an example. The ’’negative deviation’’ of the on-bevel electrical junction from the metallurgical junction is much more serious in the case of epi with buried layers, unless the epi-doping level is ≳1×1017 atoms/cm3. Various cases of surface charge effect have also been investigated. It is found that surface charge arising from deep-level surface states exhibits a self-moderating effect, in contrast to a fixed amount of surface charge from shallow states.
Shear modulus gradients in adhesive interfaces as determined by means of ultrasonic Rayleigh waves
Authors: Knollman G. C. , Hartog J. J.
Published: February 2003

Rayleigh surface waves at ultrasonic frequency have been utilized to determine shear modulus variations in the vicinity of adhesive-adherend interfaces. The measurement technique is that of acoustic critical-angle reflectivity conducted at sequentially exposed surfaces of adhesive through the interfacial accommodation zone toward the bondline. Basic theory is presented for determining shear modulus from measured Rayleigh critical angles at adhesive surfaces. Laboratory ultrasonic Rayleigh wave apparatus and its evaluation are described. Experimental procedures for sample preparation and measurement are discussed. Results of Rayleigh critical-angle reflectivity measurements on two different types of adhesives display a decided gradient in shear modulus through the interfacial region. Reference is made to other applications of the ultrasonic Rayleigh wave approach in studying the shear properties near the bondline of adhesive materials.
Instabilities in the growth of AlxGa(1−x)As/Al/AlyGa(1−y)As structures by molecular beam epitaxy
Authors: Okamoto K. , Wood C. E. C. , Rathbun L. , Eastman L. F.
Published: February 2003

Growth of epitaxial (Al,Ga)As/Al/(AlGa)As by molecular beam epitaxy was not found successful. Thermal expansion coefficient mismatch between Al and GaAs and reduction of Al melting point by partial dissolution of incident Ga and As species and with species diffusing across the metal-semiconductor interface, make epitaxial (AlGa)As growth on Al above ∼300 °C impossible. Below ∼200 °C GaAs tends to be polycrystalline. Even below 480 °C GaAs becomes semi-insulating by high deep level concentrations.
Simple stress formula for multilayered thin films on a thick substrate
Authors: Vilms J. , Kerps D.
Published: February 2003

A simple formula for stress produced by differential thermal contraction in a multilayered structure composed of thin layers on a thick substrate is derived. Formulas for bending radius and substrate stress are also given. Numerical results agree with more complicated calculations of prior work.
Nonlinear behavior of the short circuit current of a solar cell with minority carrier lifetime dependent on the light intensity
Authors: Augelli V. , Vasanelli L. , Leo M. , Leo R. A. , Soliani G.
Published: February 2003

The charge carrier transport in a solar cell is studied taking into account the dependence of the minority carrier lifetime on the injection level. The nonlinear continuity equation so obtained is solved by using a perturbative method. The spectral response of a silicon solar cell at high light intensity is evaluated on the basis of the proposed model. Theoretical results agree very well with some recently reported experimental data, for silicon solar cells at high intensity. However, there is evidence that in the light intensity range where our perturbative approach can be applied, the effect of the nonconstant minority carrier lifetime on the total short circuit current of the solar cell is quite small.
Effects of random fields on the phase diagram of Mn0.957 Zn0.043F2
Authors: Shapira Y.
Published: February 2003

The phase diagram of Mn0.957Zn0.043F2 was measured in magnetic fields H↘ up to 175 kOe, directed along the easy axis. The para-antiferro transition, at T∥C(H), shows an increased roundling at finite H. At low H, the slope −dT∥Cd(H2) is considerably larger than predicted by mean field theory. The paraspinflop boundary exhibits a much larger ’’bulge’’ than in pure MnF2. All these features are attributed to random fields. Several discrepancies from early predictions for the effects of random fields are noted, and are attributed to the absence of a genuine order-disorder transition on the line T∥C (except at H = 0).
Temperature dependence of the easy direction of magnetization of HoNi single crystal
Authors: Sato K. , Iwasaki S. , Isikawa Y. , Mori K.
Published: February 2003

The temperature dependence of the magnetic torque of a single crystal of HoNi was measured from 4.2 to 22.3 K in magnetic fields up to 18.7 kOe. The torque curves showed a twofold symmetry in the ab as well as ac plane. On the other hand the torque curve in the bc plane had a four-fold component below 15 K and then above 15 K it showed only a twofold symmetry. The experimental results indicate the electrical resistivity and magnetization anomalies at about 13 K are due to an incline of the easy direction of magnetization about 61° from the c axis in the bc plane at 4.2 K and above 15 K the easy direction of magnetization is the b axis.
A study of the rapid change of the molecular moment in Ho(Co1−c Nic)2
Authors: Tari A.
Published: February 2003

The cobalt-rich end of the series Ho(Co1−cNic)2 has been studied by spin-echo NMR of 165Ho and by magnetization measurements. From the NMR data a value of (9.55±0.11) μB is estimated for holmium in HoCo2. Magnetization measurements on the same compound give (7.9±0.1)μB for the molecular moment. An assumption of (0.8±0.2) μB for the average cobalt moment μ̄ leads to (9.5±0.4)μB for holmium in agreement with the value estimated from NMR data. Nickel substitution causes a rapid fall in the hyperfine field while the molecular moment shows a simultaneous increase with increasing nickel content. This is attributed to a bootstrap process involving the exchange field and the magnitude of the cobalt moment. This process appears to be more effective when the value of the cobalt moment is in the vicinity of 0.8μB.
Low-temperature annealing behavior of Se-implanted GaAs studied by high resolution Rutherford backscattering channeling
Authors: Bhattacharya R. S. , Pronko P. P. , Ling S. C.
Published: February 2003

High resolution Rutherford backscattering (RBS) and channeling measurements have been used to study the recrystallization of Se-implanted GaAs layers. Investigation of the solid phase growth kinetics at temperatures between 200 and 600 °C showed that the amorphous layer starts to regrow at 200 °C epitaxially from the crystalline-amorphous interface but stops, at 200 °C, after about 30% of the layer has regrown. For temperatures of 250 °C and above complete regrowth occurs. Although various amounts of disorder remain, it decreases in amount with increasing temperature. One step annealing at 600 °C for 30 minutes results in a RBS channeling quality comparable to the undamaged crystal.
Basal orientation aluminum nitride grown at low temperature by rf diode sputtering
Authors: Aita C. R.
Published: February 2003

Aluminum nitride films with solely a (0001), or basal crystallographic orientation have been grown on single-crystal silicon and silicon dioxide-coated silicon at substrate temperatures below 100 °C. The deposition technique used was rf diode sputtering of an aluminum target in argon/nitrogen gas mixtures containing 50–100% nitrogen. Unintentional oxygen doping of the growing films was minimized by a target clean-up procedure which was monitored by glow discharge mass spectrometry. X-ray diffraction measurements on the films included relative integrated intensity, peak half width, and precise peak position from which the lattice constant normal to the basal plane was calculated. The preliminary results of a study of the evolution of film crystallography from multiorientation aluminum to single-orientation aluminum nitride as the sputtering gas nitrogen content is increased are also presented.
Abstract: Polarized electrons and surface magnetism in metals (invited)
Authors: Siegmann H. C.
Published: February 2003

Various techniques including photoemission and scattering of spin polarized electrons have established some facts on magnetism of well-defined surfaces of ’’simple’’ metals: (i) there are no dead layers on Fe, Co, Ni, Gd, and others; (ii) the surface magnetization Ms often is linear over a wide range of the temperature T; (iii) depending on the ratio of bulk to surface induced anisoptropies, surface hysteresis loops may or may not differ from the ones measured in the bulk; (iv) Ms can be enhanced or reduced by adsorbates like H, S, O, C, or CO. Antiferromagnetic Cr displays the full range of the complex possibilities: it does not photoemit polarized electrons from the nonreconstructed (100)-surface even when covered with O. If, however, O is under the first layer, Ms≳O up to Tc⩽200 °C.1 It is shown that scattering of slow spin polarized electrons on glassy metallic ferromagnets allows probing of the atomic exchange correlation scattering potentials of, e.g., Fe and Ni.2 This established a basis for determining surface magnetic structures and their dependence on T by spin polarized LEED. Simpler ways of detecting electron spin polarization3 make possible more sophisticated photoemission as well as inelastic electron scattering experiments,4 promising very rapid growth of this field.      1F. Meier, D. Pescia, T. Schriber (private communication) (unpublished).  2S. W. Wang, D. T. Pierce, R. J. Celotta, J. Unguris, and H. G. Seigmann (unpublished).  3R. J. Celotta, D. T. Peirce, H. C. Seigmann, and J. Unguris, Appl. Phys. Lett. 38, 577 (1981); M. Erbudak and N. Miller, Appl. Phys. Lett. 38, 575 (1981); G. Ravano and H. Erbudak (unpublished).  4H. C. Seigmann, D. T. Pierce, and R. J. Celotta, Phys. Rev. Lett. 46, 452 (1981).
Iron and nickel as magnetization standards
Authors: Graham C. D.
Published: February 2003

Available data on the absolute magnetization of nickel and iron at room temperature are reviewed, with the aim of finding the best values to use when these materials serve as calibration standards. The field dependence of magnetization is not negligible. Recommended values of magnetization are given at 21 °C and 10 kOe, with correction factors for other temperatures and fields.
High-frequency sound as a probe of exchange energy in nickel
Authors: Alexandrakis G. C. , Devine R. A. B. , Abeles J. H.
Published: February 2003

The experiments performed at 9.37 GHz involve excitation of sound at ferromagnetic resonance via magnetoelastic coupling, its propagation through thick Ni samples, and reconversion to microwaves. In the ω-k plane there is a substantial angle between the ω axis and the phonon dispersion relation. The intersection of the phonon and spin wave dispersion occurs at a wave vector for which a large part of the spin wave energy is due to exchange. It is for this reason that sound is particularly appropriate for measurement of exchange energy.
Determination of anisotropy field in polycrystalline lithium ferrites from FMR linewidths
Authors: Brower C. J. , Patton C. E.
Published: February 2003

A technique for separating anisotropy and porosity induced FMR line-broadening contributions in narrow linewidth polycrystals has been extended to large linewidth lithium ferrite materials. The FMR linewidth is measured versus frequency and temperature T. Since the porosity contribution is proportional to the magnetization 4πMs, and the anisotropy field Ha falls off much faster at high T than does 4πMs, the two contributions to the linebroadening can be separated. Three samples were studied: Li-ferrite with and without cobalt addition (0.01 Co atoms/formula unit), and a Li-ferrite with 0.01 Co and 0.26 Ti at./f.u. The anisotropy field for unsubstituted Li-ferrite was found to decrease monotonically with T with Ha≊ 350 Oe at 25 °C, in agreement with single crystal data. Cobalt addition was found to decrease the room temperature Ha in the Li-ferrite without titanium but not in the Li-Ti-ferrite. This agrees with previous observations of Ti decreasing the effectiveness of Co in reducing the anisotropy.
Neutron polarization analysis measurements on the spiral phase of MnP
Authors: Moon R. M.
Published: February 2003

Neutron polarization analysis experiments have been used to remove a long-standing uncertainty in the details of the spiral structure of MnP. With this technique the scattering from orthogonal components of the magnetic moment can be measured separately. For the 2±δ,0,0) satellites, the ratio of spin-flip scattering (c-axis components) to spin-non-flip scattering (b-axis components) is 1.091±0.007. This result can be interpreted either in terms of an elliptical spiral or in terms of a distorted circular spiral with bunching along the easy axis. The issue was resolved in favor of the bunching model by finding third-order satellites of the correct intensity.
Structural and magnetic properties of Y(Al1−xFex)12
Authors: Yang Y. C. , Long G. J. , James W. J. , Yeh R.
Published: February 2003

In order to investigate the magnetic behavior of 3d atoms in the ThMn12-type structure, the structured and magnetic properties of Y(Al1−xFex)12 were studied by Mössbauer spectroscopy and magnetization measurements. The Y(Al1−xFex)12 intermetallic compounds crystallize in the ThMn12-type structure for x in the range of 0.3–0.5. The results can be explained on the basis of the preferential atomic ordering observed in the ternary compounds. The compounds are ferromagnetic with Curie temperatures of 130, 170, and 280 K, respectively, for x values of 0.3, 0.4, and 0.5.
SDW state for Cr metal and dilute Cr-V and Cr-Mn alloys
Authors: Ukai T. , Mori N.
Published: February 2003

The approximate d bands for Cr metal in antiferromagnetic SDW state are formulated in the tight binding approximation. It is shown that the antiferromagnetic SDW state with the periodicity extending to 21 times the lattice constant has the minimum electronic energy by using these energy bands. The d bands for Cr metal in SDW state including the spin-orbit interaction are also formulated, and stable spin configuration is investigated by comparing the free energy calculated by these energy bands. It is found that the longitudinal SDW state is stable in low temperatures, and spin flip takes place between 100 and 150 K near 4.428 d electrons per atom. Some inspection is done about the various magnetic states for dilute Cr-V and Cr-Mn alloys, and good explanation is obtained for the experimental results.
Electrical resistivity of the Kondo lattice
Authors: Lavagna M. , Lacroix C. , Cyrot M.
Published: February 2003

The electrical resistivity of the Kondo lattice is studied within the model of Lacroix and Cyrot1: In this model the Kondo fluctuations are described by a ficticious s.f. hybridization Jx/2, where x is determined self-consistently. Thermal and spatial fluctuations of the parameter x are found to play an important role in the transport properties. At low temperatures the resistivity depends strongly on the conduction electron number n: We find for n<1 a metallic behavior with a linear increase of the resistivity and a maximum at a temperature T1∼(1−n)1/3 TK. For n = 1 the resistivity is that of a semiconductor: π∼exp(TK/T). At higher temperature (above TK) the system may be treated as a collection of incoherent Kondo impurities and the resistivity exhibits a logarithmic decrease as can be expected.
Electron transport in Pd2MnSn
Authors: McAlister S. P. , Shiozaki I. , Hurd C. M.
Published: February 2003

We report measurements of the resistivity, magnetoresistivity, Hall effect, and magnetization on the ferromagnetic Heulser alloy Pd2MnSn. The results show the different manifestations in the galavanomagnetic properties of spin-disorder scattering, spin-orbit coupling, and the freezing out of spin-flip processes.
Search for magnetism in hcp ε-Fe
Authors: Cort G. , Taylor R. D. , Willis J. O.
Published: February 2003

We report the results of our recent experimental investigation which extends the search for magnetic ordering in the high-pressure, hcp phase of iron (ε-phase) to a temperature of 0.030 K. Mössbauer effect measurements were performed in the pressure range from atmospheric pressure to 21.5 GPa on a foil of natural iron (doped with 57Co). Measurements were made of the properties of both the α- and ε-phase constituents of the sample. No measurable magnetic hyperfine field was observed in the ε-phase from any of the spectra at pressures as high as 21.5 GPa and temperatures as low as 0.030 K.
Brillouin scattering of light by spin waves in thin ferromagnetic films (invited)
Authors: Grünberg P. , Cottam M. G. , Vach W. , Mayr C. , Camley R. E.
Published: February 2003

The new technique of Brillouin scattering from spin waves has been applied to thin ferromagnetic films. Scattering from standing spin waves and the Damon Eshbach (DE) surface wave is observed. The interaction of both types of waves at a mode crossing in Fe films under variation of the thickness d is investigated. The results suggest the absence of surface anisotropy and pinning. For d≲20 nm scattering from standing modes becomes too weak to be observed. In contrast to this, for the DE mode there is a strong increase in the scattering intensity when the films have been evaporated onto the proper substrates. It is shown that this is due to both an increase in the thermal DE mode amplitudes and multiple interference effects in the lightscattering process. Very strong scattering is obtained from films with d≊5 nm. There is also a remarkable Stokes-Antistokes asymmetry, which persists down to d≲3 nm. It comes from the elliptical spin-precession characteristic for such small values of d and the strong metallic attenuation of the light. The technique has also been applied to an investigation of the coupling of DE modes in double layer systems.
The Fermi surface and Fermi liquid properties of periodic Kondo and mixed valence systems
Authors: Martin Richard M.
Published: February 2003

The nature of the Fermi liquid in strongly interacting periodic systems is considered utilizing the Luttinger sum rule on the volume of the Fermi surface. The most striking conclusions are found for the Kondo lattice problem, where the ’’localized’’ f electrons modify the Fermi surface qualitatively. Related effects are well-known in impurity cases, e.g., the Kondo problem, where the analogous Friedel sum rule is satisfied by collective enhancements of the susceptibility and specific heat. The unique features of the periodic Fermi liquid are the existence of a sharp Fermi surface, the anomalous properties of which are susceptible to direct experimental measurements. It is proposed that CeX3(X = Al, Sn, or Pd) compounds are good examples and that measurements of the Fermi surface in high magnetic fields can provide definitive experimental tests.
Properties of the periodic Anderson Hamiltonian: Calculations on finite cells
Authors: Jullien R. , Martin R. M.
Published: February 2003

We present calculations for the ground state and the lowest excited states of the one-dimensional periodic Anderson Hamiltonian with two electrons per site and arbitrary magnitude of the repulsion parameter U. We present exact numerical results for finite cells (up to N = 4) and introduce ’’modified’’ periodic boundary conditions to facilitate the extrapolation for larger N. The lowest energy excitations for adding or subtracting an electron show that the system is insulating, and the lowest spin-flip excitations indicate a near instability to antiferromagnetism due to the ’’nesting’’ of the Fermi surface in 1d. For N = 4 the results agree well with infinite cell calculations both for small U and for large U in the Kondo lattice limit. The primary results are the continuous variation from the U = 0 to the Kondo lattice and mixed valence regimes and the importance of correlations, omitted in the impurity calculations, which lead to an insulating gap and dispersion in the electronic and magnetic excitations.
Ferromagnetism and spin glass ordering in transition metal alloys (invited)
Authors: Crane S. , Carnegie D. W. , Claus H.
Published: February 2003

Magnetic properties of transition metal alloys near the percolation threshold are often complicated by metallurgical effects. Alloys like AuFe, VFe, CuNi, RhNi, and PdNi are in general not random solid solutions but have various degrees of atomic clustering or short-range order (SRO), depending on the heat treatment. First, it is shown how the magnetic ordering temperature of these alloys varies with the degree of clustering or SRO. Second, by systematically changing this degree of clustering or SRO, important information can be obtained about the magnetic phase diagram. In all these alloys below the percolation limit, the onset of ferromagnetic order is probably preceded by a spin glass-type ordering. However, details of the magnetic phase diagram near the critical point can be quite different alloy systems.
Abstract: Mean-field description of spin glasses: Comparison of theory and experiment
Authors: Monod P. , Bouchiat H.
Published: February 2003

The results of mean-field models 1–3 of the spin-glass state are reviewed with emphasis on the temperature and magnetic field dependence of the susceptibility and the nonlinear magnetization near the spin-glass temperature Tg. These models fail below the temperature defined by De Almeida and Thouless4 where the projection hypothesis3 is made. In order to test this overall description, a good knowledge of the equilibrium magnetizaton of the spin glass is needed. We present our results for the field cooled magnetization of a Ag-Mn alloy (10.6 at. % Mn) from which a tentative H-T phase diagram is drawn for the existence of the spin-glass phase.5 Measurements of the nonlinear component of the magnetization near Tg allow us to define the critical exponents γ and δ for the divergence of the field-induced order parameter above Tg. We find5 γ = 1.50±0.5 and δ∼2, to be compared with the values of 1 and 2, respectively, from the mean-field model.2 These results are compared to other determinations6–8 on similar systems from which a scaling function for the nonlinear magnetization is determined. There is no agreement at present between these experimental results.     1D. Sherrington and S. Kirkpatrick, Phys. Rev. Lett. 32, 1792 (1975). 2M. Suzuki, Prog. Theor. Phys. 58, 1151 (1977). 3G. Parisi and G. Toulouse, J. Phys. Lett. 41, 361 (1980). 4J. R. L. De Almedia and D. J. Thouless, J. Phys. A 11, 983 (1978). 5H. Bouchiat, thèse de 3e cycles, Orsay, 1981 (unpublished); P. Munod and H. Bouchait, Disordered Systems and Localized Conference Proceedings, Rome, 1981 (in press) and J. Phys. Lett. (in press). 6B. Barbara, A. P. Malozemoff, and Y. Imry, Phys. Rev. Lett. (unpublished). 7A. Berton, J. Chaussy, J. Odin, R. Rummal, and R. Tournier (unpublished). 8Y. Miyako, S. Chikazawa, T. Saito, and Y. G. Yochunas, J. Appl. Phys. 52, 1779 (1981).
Abstract: ESR study of a Ni-Mn spin-glass alloy
Authors: Hurdequint H. , Kouvel J. S. , Monod P.
Published: February 2003

Electron spin resonance (ESR) measurements at fixed frequency (∼9 GHz) were made on a disordered Ni-Mn alloy of ∼26 at. % Mn which has typical spin-glass properties below Tg∼80 K. For the alloy cooled to 4 K in zero field, a broad resonance was observed whose position in field indicates the existence of an effective anisotropy field HA parallel to the magnetization M. After cooling to 4 K in +10 kOe, equally intense but sharper resonances were seen at the positive and negative fields that are unequal in magnitude, although M at these two fields is essentially equal and opposite. The unidirectional component of HA thus determined agrees closely with the field displacement of the magnetic hysteresis loop, for which the two negative coercivities are evidenced in the ESR spectrum at low fields. Upon warming, the field asymmetry of the ESR spectrum decreases rapidly and disappears at ∼25 K, where HA has become entirely uniaxial (reversing completely with M) though its magnitude is almost unchanged. At higher temperatures, HA decreases steadily and vanishes just above Tg. These results extend significantly beyond those of an earlier ESR study of Ni-Mn, for which the resonances in fields parallel but not antiparallel to the field applied during cooling were reported.1     a) Permanent address: Physics Department, University of Illinois at Chicago, Chicago, IL 60680. Work supported in part by NSF Grant No. DMR78-12777. 1 V. S. Pokatilov, I. M. Puzei, and G. A. Ivanov-Smolenskii, Sov. Phys. Solid State 21, 97 (1979).
Crystallization kinetics in Fe−B−Si metallic glasses
Authors: Ramanan V. R. V. , Fish G. E.
Published: February 2003

Crystallization kinetics of Fe-B-Si metallic glasses, as characterized by the effective activation energy Ec and the Avrami exponent n have been studied using Differential Scanning Calorimetry. The data show that in the hypoeutectic (Fe-rich) region, the glasses crystallize into α-(Fe,Si) and Fe3B in that order. The growth of crystallites is diffusion controlled, and Ec falls off rapidly away from the eutectic trough. In the hypereutectic region, both crystalline phases are obtained simultaneously. Thermal stability is greatly enhanced by addition of Si(∼3 at. %) and the growth process is no longer purely diffusion controlled. The behavior of Ec and n versus composition is discussed. Effects on Ec and n of additions of small amounts of Ni and Mo are also reported. Such additions have direct relevance to the design of new glasses for applications at high frequencies.
Electrical resistivity and Hall effect in Fe-Zr amorphous sputtered films
Authors: Fukamichi K. , Gambino R. J. , McGuire T. R.
Published: February 2003

Fe-Zr amorphous films were prepared by a co-sputtering technique, and the electrical resistivity and the Hall effects were investigated. The resistivity ρ at 4.2 K as a function of composition exhibits a broad minimum around 15% Zr, while the magnetization 4πMs indicates a broad maximum at the same composition. The high-field susceptibility dramatically increases below 15% Zr. In the high concentration range the spontaneous Hall coefficient Rs and the magnetization 4πMs decrease, while the resistivity increases, and hence the Hall conductivity γH decreases with increasing Zr content. The ordinary Hall coefficient R0, separated from the spontaneous Hall coefficient Rs, slightly increases with increasing Zr content, showing a positive sign in contrast to that of Co and Ni-base amorphous alloys.
Perpendicular anisotropy of bias-sputtered GdCo film
Authors: Kusuda Tetsuzo , Honda Shigeo , Ohkoshi Masatoshi
Published: February 2003

Some important information about the structural change of GdCo sputtered film with substrate bias is obtained by using the replica technique. It is found that the increase in perpendicular magnetic anisotropy for increasing substrate bias is related directly with the ultrafine microstructure of the GdCo film. The relative substrate potential with respect to the Ar plasma depends either on Ar pressure during sputtering or on the external substrate bias. When this relative substrate potential becomes negative by a certain amount, sputtering of surface oxygen and resputtering of Gd in the growing film will be initiated, and consequently the structure of sputter-deposited film will change. The origin of microscopic perpendicular magnetic anistropy with or without substrate bias is described by a model proposed earlier for Permalloy films. The perpendicular magnetic anisotropy based on this microscopic shape anisotropy model is Ku = 2πMs2(δ/a), where δ is the thickness of the nonmagnetic boundary and ’’a’’ is the columnar diameter of the magnetic body. The quality factor Q is expressed as Q = (δ/a). These relations explain fairly well the increase in Ku with increasing negative bias voltage.
Magnetic properties of amorphous GdFeB and GdCoB alloys
Authors: Taylor R. C. , Gangulee A.
Published: February 2003

Studies have been made of the magnetization of GdFeB and GdCoB amorphous thin films in which ratios of Gd to transition metal and B to transition metal were varied. In GdCoB alloys the Co moment decreases as the sum of the B and Gd concentration increases. Assuming a charge transfer mechanism, each Gd contributes 1.4 electrons and each B 2.1 electrons to the Co 3-d band. The moment can be described by an additive charge transfer equation. However, in GdFeB alloys the Fe moment increases with increasing B concentration beyond a boron to iron ratio of 0.15. In addition to a reduction in Fe moment by charge transfer of 2.1 electrons from Gd and 2.4 from B, there is an increase in Fe moment due to B addition at higher concentrations. A possible cause for this behavior can be found in the noncollinear (sperimagnetic) alignment of the Fe magnetic sublattice in amorphous ferrimagnetic alloys. High field susceptibility data show that sperimagnetism is reduced with increasing boron.
Sputtering-induced recrystallization on the target and its effect on magnetic properties of amorphous rare-earth transition metal thin films
Authors: Chen Tu , Malmhäll R. , Charlan G. B.
Published: February 2003

An investigation was made to evaluate the variation in the magnetic hysteretic properties of rf-sputtered amorphous Tb-Fe thin films as a function of sputtering parameters, such as Ar pressure and rf input power. It was discovered that, during sputtering from a composite target which consists of rare-earth disks placed on a transition metal plate, the average surface composition of the target changed by formation of intermetallic RE-TM compounds through a recrystallization process on the RE disk surface. Using x-ray diffraction, electron microprobe, and scanning electron microscopy, analysis of the surface revealed that the amount and morphology of intermetallic compounds formed had a strong dependence on Ar pressure but a lesser dependence on power. The magnetic properties of the films deposited under different sputtering conditions were measured using Kerr magneto-optic and VSM hysteresis loop tracers. The results show that the changes in the magnitude of magnetization, coercivity, and polarity of the hysteresis loop of the films obtained from a given sputtering target with various sputtering parameters are the consequence of changes in film composition which arise from the altered surface composition and morphology of the sputtering target.
Further studies of nonlinear susceptibility of GdAl and MnCu spin glasses
Authors: Malozemoff A. P. , Barbara B. , Imry Y.
Published: February 2003

Further data and experimental details are given, complementing our earlier report of scaling of the nonlinear susceptibility χ(H,T) as a function of field H and temperature T of two classic spin glasses. In particular, scaling for T<Tf is found to be relatively temperature independent.
High-temperature susceptibility of cobalt and manganese aluminosilicate glasses
Authors: Morgownik A. F. J. , Mydosh J. A. , Wenger L. E.
Published: February 2003

The magnetic susceptibility for 14.3 at.% Mn and 14.3 at.% Co aluminosilicate glasses has been measured via a sensitive pendulum magnetometer from 4 to 300 K in a field of 5 kOe. For temperatures above 80 K a Curie–Weiss law was obeyed in both systems; however, below 80 K strong deviations from this law occurred. From the high-temperature inverse susceptibility, a Bohr magneton number p0 of 5.93 μB for Mn and 4.73 μB for Co was found. These values correspond to the free ion values observed for Mn++ and Co++, respectively. The paramagnetic Curie temperatures ϑ are −117 K for Mn and −44 K for Co. Assuming a cubic closed packed structure to represent our amorphous system, we have analyzed these results with a canonical ensemble for all possible states of the first eleven configurations in which magnetic impurities can be grouped in this structure. Thereby we can explain the deviations from the Curie–Weiss law, ϑ, and p0 and their temperature dependences with nearest neighbor and next nearest neighbor exchanges of −27 and −20 K for Mn and −24 and +5 K for Co.
Magnetic viscosity in spin glass Fe-Ni-B-Si amorphous alloys
Authors: Kudo T. , Egami T. , Rao K. V.
Published: February 2003

The magnetic viscosity near the ferromagnet to spin glass transition was studied for amorphous (Fe-Ni)75 B15 Si10 alloys. The spin glass transition temperature Tf was defined by the maximum in the viscosity versus temperature plot measured at low fields. The result strongly suggests the presence of a well defined line of transition between ferromagnetic to spin glass, over a range of composition.
Contrasts in the coercivities of SmCo5 and Sm2Co17-type permanent magnets
Authors: Leupold H. A. , Rothwarf F. , Breslin J. T. , Winter J. J. , Tauber A. , Paul D. I.
Published: February 2003

We have extracted the intrinsic coercivity, saturation magnetization, and anisotropy field from M-H loop measurements in the TDK Sm2(Co, Fe, Cu, Zr)17 and the Hitachi SmCo5 permanent magnetic materials from liquid helium to room temperature. The TDK sample exhibits a coercivity in the hard direction which is larger than in the easy direction, while the reverse situation is true for the SmCo5 sample. This behavior is linked to the difference in the mechanisms of magnetization dominating the sample, wall domain motion for the TDK sample, and domain nucleation for the SmCo5.
rf-sputtered Sm-Co films: Phase stability and magnetic properties
Authors: Cadieu F. J. , Aly S. H. , Cheung T. D. , Pirich R. G.
Published: February 2003

We have rf-sputtered films of the Sm-Co system for the composition region near the 1–5 and 2–17 compounds. The sputtering target arrangement was such that a range of compositions was deposited along the length of the substrates. The substrate temperature was varied for different runs from room temperature, in which case amorphous film could be synthesized, to 1000 °C. Magnetization measurements of crystalline films sputtered onto heated substrates exhibit increasing remanence and decreasing coercivity as the film composition varies from the SmCo5 to the Sm2Co17 regions. Magnetization as a function of orientation and x-ray data indicate that the c axis, which in this case is the easy direction of magnetization, lies near or in the plane of the film for these samples. The variation of the magnetization for different magnetizing fields indicates that the coercivity is controlled both by domain wall-pinning and by nucleation mechanisms.
Mössbauer study of structural relaxation in amorphous YFe2 and Fe16Ni62B14Si8
Authors: Nishihara Y. , Katayama T. , Ogawa S.
Published: February 2003

Mössbauer effect of 57Fe in the paramagnetic phase of amorphous YFe2 and Fe16Ni62B14Si8 was measured to investigate a microscopic mechanism of structural relaxation. The Mössbauer spectrum broadens after annealing around 100 °C for YFe2. On the other hand, broadening appears around 100 and 250 °C in Fe16Ni62B14Si8. These broadenings are attributed to disturbances of environment around iron caused by movements of constituent atoms. The quadrupole splitting becomes small owing to a development of topological atomic short range ordering by the annealing in both samples. From these results it is concluded that the structural relaxation of metal-metalloid glass is divided into two stages. The first stage, below ∼250 °C, is an alloying process between metal atoms. The second stage, above ∼250 °C, is an incipient process of crystallization which is caused by a movement of metalloid atoms.
Magnetic properties of amorphous YFe2 prepared by melt-spinning
Authors: Croat J. J. , Herbst J. F.
Published: February 2003

We have prepared amorphous YFe2 by the melt-spinning technique and compared its magnetic properties with those of crystalline YFe2. The amorphous material is ferromagnetic with a Curie temperature of ∼270 K, versus 548 K for its crystalline counterpart. In a 16 kOe applied field the low-temperature moment of the amorphous sample is 1.30 μB per Fe ion, slightly smaller than the 1.43 μB value observed for the crystalline sample. No significant coercivity is found in either case, even at the lowest temperatures. Simple molecular field theory satisfactorily describes the temperature dependence of the magnetization for crystalline YFe2 but is less adequate for the amorphous material.
Abstract: Transverse susceptibility and magnetization of transverse field annealed Metglas 2605CO
Authors: Hernando A. , Aroca C. , Madurga V. , Savage H. T.
Published: February 2003

Amorphous Fe-B base ribbons have been shown to have large magnetoelastic coupling1 when appropriately annealed in a transverse magnetic field. The domain structure of Metglas 2605CO (Fe67Co18B14Si1), when annealed as above, was observed by a Bitter technique. The magnetization of each domain is entirely transverse with the main Bloch walls normal to the axis of the ribbon. The domain width is about 0.3 mm. Longitudinal magnetization measurements indicate a rotational magnetization process. We have measured χyy and χyz (y normal to, and z along the axis of the ribbon) by passing an ac current through the ribbon in the presence of a bias field. χyy is defined as the susceptibility determined from the voltage drop along the ribbon. χyz is defined as the susceptibility determined from the voltage of a pickup coil wound around the sample. Anomalous structure is seen in values of χyy between 10 and 100 kHz. We speculate that transverse magnetoelastic resonances are the cause of the structure. The overall reduction in χyy as a function of frequency is larger than can be explained by normal eddy current analysis. Transverse magnetization loops at several longitudinal biases have been measured and show a strong nonlinearity as a function of the current.   Metglas is a registered trademark of the Allied Chemical Corporation.  1 C. Modzelewski, H. T. Savage, L. T. Kabacoff, and A. E. Clark, IEEE Trans. Magn. MAG-17, 2837 (1981).
Low-temperature specific heat, ac susceptibility, and electrical resistivity of amorphous Fe90Zr10, Co90Zr10, and Co86Zr14 alloys
Authors: Obi Y. , Wang L. C. , Motsay R. , Onn David G. , Nose M.
Published: February 2003

The low-temperature specific heat (CP) and magnetic susceptibility (χ) for the amorphous alloys Fe90Zr10, Co90Zr10, and Co86Zr14 are presented. A very large linear contribution to CP combined with a sharp decrease in χ below about 60 K show Fe90Zr10 to have spin-glass or spin-cluster glass behavior at low temperatures. The Co-based alloys show no deviations from true ferromagnetic behavior at low temperatures. Values of the Debye temperature for all three alloys and the electronic density of states for the Co-based alloys are obtained.
Rapid diffusion in garnets doped with Si, Ge, or Ca
Authors: Gyorgy E. M. , LeCraw R. C. , Luther L. C.
Published: February 2003

It has been known for some time that Si additions to YIG reduce the magnetostrictive constants to zero. However, attempts to produce bubble garnets with a large uniaxial anisotropy Ku and zero magnetostriction have failed, since, as the Si or Ge concentration is increased, Ku markedly decreases. It is the purpose of this paper to show that this decrease of Ku is not the result of the dopant interfering with the preferential occupation of the rare earths on the dodecahedral sites during growth, but rather that the presence of the dopant increases the diffusion rate to such an extent that Ku is substantially annealed out during the growth time. The addition of Ca also increases the diffusion rate but not to the same extent as do Si and Ge. Similar increases in the intersite diffusion rate of Ga and Fe, as measured by changes in 4πM, were observed in (Y La)3(Ga Fe)5O12(Si).
Potential barrier study of the border-line defined by ion implantation in bubble garnets
Authors: Pougnet P. , Jouve H. , Gerard P. , Humphrey F. B.
Published: February 2003

This paper describes an experimental investigation of the potential barrier existing at the border of an implanted region. The technique consists of taking high speed photography pictures of a bubble moving across this barrier or away from it with the help of gradient drive fields. Results are presented for samples implanted with Ne+ 200 keV (0.5–5)×1014 unannealed and annealed subsequently up to 700 °C. A bubble is in a stable position in the implanted region when its domain wall is pinned at the border. The magnitude of the potential barrier separating the two regions is found to be 8×10−8 erg. The energy minimum corresponding to the bubble stable position is very sharp. When ion dosage increases up to 5×1014, the forces holding the bubble into the minimum do not appear to saturate. Under annealing from 300 to 700 °C, all the forces involved by the barrier decrease monotonically. A model is presented which gives a good account of the shape and the magnitude of the potential barrier.
Study of magnetic properties and Mössbauer effect of Fe-Cr-Co permanent magnetic alloys
Authors: Ming-Yan Chen , Hui-Juan Wang , Yong Yan , Han-Ru Shao , De-Xin Li , Wen-Gui Lin , Guo-Dong Li
Published: February 2003

Different cobalt-containing samples of Fe-Cr-Co alloys in the same heat-treatment conditions are investigated by means of Mössbauer effect (ME), ferromagnetic resonance (FMR),and magnetic measuring techniques. The magnetic phase, the reverse-magnetization mechanism, and the influence of cobalt content of these alloys on their PM properties are analyzed and discussed.(AIP)
Study of domain formation in small permalloy magnetoresistive elements
Authors: Tsang C. , Decker S. K.
Published: February 2003

Our past work has shown that the Barkhausen noise in the transverse response of small (10–100 μm) permalloy MR sensors originates from domain wall activities; namely, the systematic creation, intensification, and wall-state transition of buckling domain structures. The cause and details of domain formation, however, remain unresolved. In this work, through direct domain observations and wall population studies, we will show that magnetostatic energy effects constitute the most basic cause of domain formation. Easy-axis dispersion (δK) effects can also cause domains, but primarily for the shorter elements. Also, we will show how the magnetic configurations along the top and bottom edges of the element affect the geometry of the resultant buckling domains, and how fluctuations in these edge configurations produce fluctuations in the domain geometry and, consequently, in the MR response. Finally, we will show that domain activities are not suppressed by different orientations of the easy axis, although interesting changes in the domain behavior may be produced.