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Microstructure Of Epitaxial Ybba2Cu3O7 Superconducting Films Grown By A New Liquid-Gas-Solidification Technique, C.H. Chen, H.S. Chen, Sy_Hwang Liou
Microstructure Of Epitaxial Ybba2Cu3O7 Superconducting Films Grown By A New Liquid-Gas-Solidification Technique, C.H. Chen, H.S. Chen, Sy_Hwang Liou
Sy-Hwang Liou Publications
We have studied the microstructures of epitaxial YbBa2Cu3O7 superconducting films grown on SrTiO3 [100] and [110] substrates by a new liquid-gas-solidification processing technique. Films grown on SrTiO3 [100] and [110] substrates are epitaxially oriented with [001] and [110] axes normal to the film surface. Twinned domains of ~200 Å in size are observed in the [001] oriented films. Most defects observed can be attributed to the presence of stacking faults along the c axis. The presence of Cu-O bilayer defects is also observed. Rapid oxygen diffusion in the liquid phase is found to …
Tunneling Characteristics Of Internal Josephson Junctions In Yba2Cu3O7-Δ Thin Films, W.S. Brocklesby, Don Monroe, M. Hong, Sy_Hwang Liou, J. Kwo, G.J. Fisanick, P.M. Mankiewich, R.E. Howard
Tunneling Characteristics Of Internal Josephson Junctions In Yba2Cu3O7-Δ Thin Films, W.S. Brocklesby, Don Monroe, M. Hong, Sy_Hwang Liou, J. Kwo, G.J. Fisanick, P.M. Mankiewich, R.E. Howard
Sy-Hwang Liou Publications
We have measured detailed I-V characteristics of small areas of YBa2Cu3O7-δ films, which exhibit structure associated with individual Josephson junctions within the film. Both hysteretic and nonhysteretic junctions are seen. A simple model relating the voltage steps to the junction properties is developed. The temperature dependence of lc for the hysteretic junctions fits that predicted for quasiparticle tunneling junctions between conventional superconductors.
Superconducting Tl-Ba-Ca-Cu-O Films By Sputtering, M. Hong, Sy_Hwang Liou, D.D. Bacon, G.S. Grader, J. Kwo, A.R. Kortan, B.A. Davidson
Superconducting Tl-Ba-Ca-Cu-O Films By Sputtering, M. Hong, Sy_Hwang Liou, D.D. Bacon, G.S. Grader, J. Kwo, A.R. Kortan, B.A. Davidson
Sy-Hwang Liou Publications
Superconducting Tl-Ba-Ca-Cu-O thin films 0.2–1.0 µm thick have been prepared on MgO(100) and SrTiO3 (100) substrates by dc diode sputtering using a single oxide target. Films containing primarily the Tl2Ba2Ca1Cu2O8 phase were obtained with a Tc (R =0) at 102 K and a transport Jc of 104 A/cm2 at 90 K. For the nearly pure phase Tl2Ba2Ca2Cu3O10 films, the Tc's (R =0) are higher at 116 K and the transport Jc's …
Magnetic And Structural Properties Of Melt-Spun Rare-Earth Transition-Metal Intermetallics With Thmn12 Structure, E.W. Singleton, J. Strzeszewski, George C. Hadjipanayis, David J. Sellmyer
Magnetic And Structural Properties Of Melt-Spun Rare-Earth Transition-Metal Intermetallics With Thmn12 Structure, E.W. Singleton, J. Strzeszewski, George C. Hadjipanayis, David J. Sellmyer
David Sellmyer Publications
The magnetic and structural properties of melt-spun R8Fe84Ti8 with R=Nd, Sm, Dy, Gd and R8 (Fe,Co) 76 [V(Mo)] 16 with R=Nd, Sm have been studied with x-ray diffraction, transmission electron microscopy, and magnetic measurements. The tetragonal ThMn12-type structure was found in all alloys after annealing at about 700 °C. The Curie temperature (Tc) of the as-spun amorphous samples was in the range of 40–100 °C. Crystallized Nd8 (Fe1-xCox)84Ti8 samples with the 1:12 structure have a Tc around 250 °C for …
Structure And Magnetic Properties Of Nanostructured Dy/Transition-Metal Multilayered Films, Z.S. Shan, David J. Sellmyer
Structure And Magnetic Properties Of Nanostructured Dy/Transition-Metal Multilayered Films, Z.S. Shan, David J. Sellmyer
David Sellmyer Publications
We report the results of magnetic and microstructural studies for T/Dy (T=Fe, Co, Ni) compositionally modulated films prepared in a multiple-gun sputtering system. The perpendicular anisotropy and magnetization were measured systematically for X-Å Fe/Y-Å Dy and X-Å Co/Y-Å Dy films. The layer-thickness dependence of the magnetization for Co/Dy and Fe/Dy was interpreted in terms of the antiparallel coupling between transition-metal and Dy magnetic moments. For Co/Dy films the ranges of X and Y required for perpendicular anisotropy were determined. A comparision of the structural and magnetic properties of Ni/Dy, Co/Dy, and Fe/Dy is given and the origin of the perpendicular …
Magnetic And Structural Properties Of Nd2Fe14B Permanent-Magnet Films And Multilayers With Fe And Ag, K.D. Aylesworth, Z.R. Zhao, David J. Sellmyer, George C. Hadjipanayis
Magnetic And Structural Properties Of Nd2Fe14B Permanent-Magnet Films And Multilayers With Fe And Ag, K.D. Aylesworth, Z.R. Zhao, David J. Sellmyer, George C. Hadjipanayis
David Sellmyer Publications
The effects of sputtering conditions on the structure and magnetic properties of Nd2 (Fe0.9Co0.1)14B films and multilayers are reported. The samples were sputtered onto temperature-controlled mica and Ta substrates, at temperatures between 20 and 620 °C. X-ray diffraction results indicate that films deposited directly onto 500–600 °C substrates with Fe buffer layers are nearly single-phase materials with the c axis of the grains largely perpendicular to the film plane. Room-temperature magnetization measurements to 17.4 kOe indicate that these films have strong perpendicular anisotropy with coercivities in excess of 10 kOe and magnetizations greater …
Electronic Structure And Surface Reactivity Of Nd2Fe14B And Related Compounds, Sitaram Jaswal, Marjorie Langell, Y.G. Ren, M.A. Engelhardt, David J. Sellmyer
Electronic Structure And Surface Reactivity Of Nd2Fe14B And Related Compounds, Sitaram Jaswal, Marjorie Langell, Y.G. Ren, M.A. Engelhardt, David J. Sellmyer
David Sellmyer Publications
Studies of electronic and magnetic structure and surface reactivity are reported for R2T14B compounds where R=Y, Nd, Gd, and T=Fe, Co. The calculations employed the self-consistent, spin-polarized linear-muffin-tin orbital method. Experiments included ultraviolet, x-ray, and Auger electron spectroscopy. Comparisons are made between the calculated and measured electronic densities of states, and the reactions of the surfaces with O2, H2, and CO gases are studied. The effects of heat treatment on surface segregation are also reported. Journal of Applied Physics is copyrighted by The American Institute of Physics.
Ferromagnetism In Metastable 304 Stainless Steel With Bcc Structure, J. Childress, Sy_Hwang Liou, C.L. Chien
Ferromagnetism In Metastable 304 Stainless Steel With Bcc Structure, J. Childress, Sy_Hwang Liou, C.L. Chien
Sy-Hwang Liou Publications
We have studied the consequence of structure on the magnetic properties of 304 stainless steel in two distinct crystalline states. Ordinary 304 stainless steel has an fcc structure and is nonmagnetic at room temperature. By using a vapor quenching method, we have fabricated single-phase metastable bcc 304 stainless steel which is strongly ferromagnetic. Films a few µm thick have been made by high-rate sputter deposition onto substrates at room temperature or liquid-nitrogen temperature. Vibrating sample magnetometry and 57Fe Mössbauer spectroscopy reveal that the bcc phase has a magnetization of 130 emu/g, due largely to the Fe moment. The Curie …
Differential Cross Sections For Secondary Electron Production By 1.5-Kev Electrons In Water Vapor, K. W. Hollman, G. W. Kerby, Iii, M. Eugene Rudd, J. H. Miller, S. T. Manson
Differential Cross Sections For Secondary Electron Production By 1.5-Kev Electrons In Water Vapor, K. W. Hollman, G. W. Kerby, Iii, M. Eugene Rudd, J. H. Miller, S. T. Manson
M. Eugene Rudd Publications
Discrepancies between previous experimental values of differential cross sections for electron-impact ionization of water vapor and recent model calculations have been largely resolved. A new measurement with improved suppression of spurious electrons has removed most of the discrepancy in the midrange of detected electron energies. A second discrepancy at secondary energies just below the primary energy has been explained by a more accurate accounting for electrons scattered at angles between zero and the minimum angle of the experimental apparatus. The improved data show more clearly the oxygen K-shell edge in the spectra at small angles and the Bethe ridge at …
Scanning Electron Microscope Identification Of Weak Links In Superconducting Thin Films, Don Monroe, W.S. Brocklesby, R.C. Farrow, M. Hong, Sy_Hwang Liou
Scanning Electron Microscope Identification Of Weak Links In Superconducting Thin Films, Don Monroe, W.S. Brocklesby, R.C. Farrow, M. Hong, Sy_Hwang Liou
Sy-Hwang Liou Publications
We have used a pulsed electron beam in a scanning electron microscope to produce highly localized (~1 µm) changes in the electrical properties of a heterogeneous thin film of YBa2Cu3O7-δ . The predominant effect of the beam is to locally heat the film, producing a measurable shift in the current-voltage characteristic. In particular, we have precisely located the part of the film responsible for a sharp feature in the current-voltage characteristic corresponding to a single Josephson junction. The technique should also be useful more generally in identifying specific weak links in superconducting thin films.
Explorers Of The Nuclear Cyclotron
Experiment 190, Robert Fuller
Explorers Of The Nuclear Cyclotron Experiment 190, Robert Fuller
Robert G. Fuller Publications
Physics is the world view espoused by the community of people called physicists. Some of them use a common facility with many other physicists to increase the cost-effectiveness of the facility. The life style of such physicists shares many features with a wide variety of professions that use very expensive equipment. For example, personal time schedule of the equipment as much for television producers as for cyclotron physicists.
Two-Photon Detachment Of The Negative Chlorine Ion, Tsin-Fu Jiang, Anthony F. Starace
Two-Photon Detachment Of The Negative Chlorine Ion, Tsin-Fu Jiang, Anthony F. Starace
Anthony F. Starace Publications
Theoretical calculations of the two-photon detachment cross section of the negative chlorine ion are presented in the energy region from threshold to the single-photon ionization threshold using a transition-matrix method. Detailed analyses are presented of the effects of various kinds of electron correlations, whose net effect is a reduction of the uncorrelated Hartree-Fock model cross sections by up to 30%. Our cross sections have a much flatter variation with energy and a much lower magnitude (by up to a factor of 2 or 3) than the frozen-core free-electron results of M. Crance [J. Phys. B 20, 6553 (1987)] or the …
Growth Of Epitaxial Ybba2Cu3O7 Superconductor By Liquid-Gas-Solidification Processing, H.S. Chen, Sy_Hwang Liou, A.R. Kortan, L.C. Kimerling
Growth Of Epitaxial Ybba2Cu3O7 Superconductor By Liquid-Gas-Solidification Processing, H.S. Chen, Sy_Hwang Liou, A.R. Kortan, L.C. Kimerling
Sy-Hwang Liou Publications
Superconductive films of YbBa2Cu3O7 have been epitaxially grown on SrTiO3 substrate by a novel liquid-gas-solidification process. A layer of metallic YbBa2Cu3 melt was coated on the substrate and in situ oxidized. The oxide films grown on the SrTiO3 (100) substrate are epitaxially oriented in structure with the c axis normal to the plane film. Values of T c (R =0) of 82 K with a transition width of 1 K have been achieved. The critical current density J c is typically 105 A/cm2 at 50 K and …
Metastable Conduction States In Mo2S3: Pulse Conductivity And Thermoelectric Power, Roger D. Kirby, R.L. Fagerquist
Metastable Conduction States In Mo2S3: Pulse Conductivity And Thermoelectric Power, Roger D. Kirby, R.L. Fagerquist
Roger Kirby Publications
Mo2S3 is a linear-chain-structure compound which has two inequivalent zig-zag Mo chains parallel to the b axis. It undergoes at least two phase transitions below room temperature (at 182 and 145 K upon cooling). X-ray-diffraction measurements show that both incommensurate and commensurate structural distortions are associated with the phase transitions. We repot here the results of electrical-conductivity and thermoelectric-power measurements on Mo2S3 . By using pulsed electric currents to rapidly heat and cool the sample while electrical-resistivity or thermoelectric-power measurement are being made, we are able to show that below the lower-temperature phase transition, …
Simulation Of The Polarizable-Ion Dynamics Of Rb2Zncl4, P. J. Edwardson, John R. Hardy
Simulation Of The Polarizable-Ion Dynamics Of Rb2Zncl4, P. J. Edwardson, John R. Hardy
John R. Hardy Papers
The promotion yet prevention of structural stability in the paraelectric phase of Rb2ZnCl4 by ionic polarizability is explored with both constant-lattice and variable-lattice simulations. As many as 168 ions ( 3 x 1 x 2 cells) under periodic boundary constraints are allowed to polarize in nonlinear response to forces which are obtained from the electron-gas model of Gordon and Kim. No assumption about the rigidity of the ZnCl42- ion is made. The cause of polarization catastrophe in linear models is examined, and a cure is implemented via nonlinearity of the dipole moment versus field strength. …
Variational Calculation Of Multiphoton Ionization Processes For The H Atom, Bo Gao, Anthony F. Starace
Variational Calculation Of Multiphoton Ionization Processes For The H Atom, Bo Gao, Anthony F. Starace
Anthony F. Starace Publications
Well-known variational principles for second-order perturbation matrix elements are extended to higher-order multiphoton processes for atomic hydrogen. Numerical applications to two- and three-photon ionization of the hydrogen ground state provide results comparable to those of analytic calculations, even near intermedaite-state resonances, yet without the complications involved in summation over intermediate states. Extensions to multiphoton processes for many-electron atoms are discussed briefly.
Dynamics Of Antimatter-Atom Collisions, R. E. Olson, Timothy J. Gay
Dynamics Of Antimatter-Atom Collisions, R. E. Olson, Timothy J. Gay
Timothy J. Gay Publications
Classical-trajectory Monte Carlo calculations have been used to study ionizing collisions between charged particles (p, p̅ , ℯ+, ℯ-) and He atoms at an incident velocity of 2.83 a.u. While differences in the total single-ionization cross sections for these projectiles are small, our calculations reveal large effects at all angles in the ionized electron spectra, and provide qualitative evidence for a Barkas effect in p and p̅ collisions. Experimental data agree well with our fully classical calculations, including cross sections involving ejected electrons of long wavelength.
Electronic Excitations Of The Yba2Cu3O7-X Superconductor: A Study By Transmission Electron-Energy-Loss Spectroscopy With An Electron Microprobe, C.H. Chen, L.F. Schneemeyer, Sy_Hwang Liou, M. Hong, J. Kwo, H.S. Chen, J.V. Waszczak
Electronic Excitations Of The Yba2Cu3O7-X Superconductor: A Study By Transmission Electron-Energy-Loss Spectroscopy With An Electron Microprobe, C.H. Chen, L.F. Schneemeyer, Sy_Hwang Liou, M. Hong, J. Kwo, H.S. Chen, J.V. Waszczak
Sy-Hwang Liou Publications
Interband and core-level transitions and plasmon resonance in the high-temperature oxide superconductor YBa2Cu3O7-x were studied by transmission electron-energy-loss spectroscopy using an electron microprobe ∼5-10 Å in size. Both single-crystal and polycrystalline ceramic samples have been examined. No significant change in electronic structure was observed at the grain boundaries. A 13.5-eV interband-transition peak was found to be sensitive to damages created by ion-beam bombardment.
Incommensurate Superlattice And 90° Twist Boundaries In The Superconducting Phase Of Bi-Sr-Ca-Cu-O, C.H. Chen, D.J. Werder, Sy_Hwang Liou, H.S. Chen, M. Hong
Incommensurate Superlattice And 90° Twist Boundaries In The Superconducting Phase Of Bi-Sr-Ca-Cu-O, C.H. Chen, D.J. Werder, Sy_Hwang Liou, H.S. Chen, M. Hong
Sy-Hwang Liou Publications
We have observed an incommensurate superlattice structure in the Bi-Sr-Ca-Cu-O system using electron diffraction. The wave vector of the superlattice, q=(0,1/4.7,1), has an incommensurate component along the b axis and a commensurate component along the c axis. Twist boundaries perpendicular to the c axis, across which the crystallographic a and b axes are rotated 90°, are commonly observed in this system.
Possible Origins Of High-TC, Superconductivity, John R. Hardy, J. W. Flocken
Possible Origins Of High-TC, Superconductivity, John R. Hardy, J. W. Flocken
John R. Hardy Papers
A new mechanism is proposed to explain high-Tc superconductivity in copper-oxide-based, open perovskitelike systems. It is shown that, should the oxygen ions be moving in a double-well potential, an order-of-magnitude enhancement of the electron-lattice coupling follows automatically from a consistent treatment of this motion. Both theoretical and experimental evidence for the presence of such double wells is cited.
Y-Ba-Cu-O Films By Rf Magnetron Sputtering Using Single Composite Targets: Superconducting And Structural Properties, Sy_Hwang Liou, M. Hong, J. Kwo, B.A. Davidson, H.S. Chen, S. Nakahara, T. Boone, R.J. Felder
Y-Ba-Cu-O Films By Rf Magnetron Sputtering Using Single Composite Targets: Superconducting And Structural Properties, Sy_Hwang Liou, M. Hong, J. Kwo, B.A. Davidson, H.S. Chen, S. Nakahara, T. Boone, R.J. Felder
Sy-Hwang Liou Publications
High Tc superconducting Y-Ba-Cu-O films have been produced by rf magnetron sputtering using single unreacted composite targets of Y2O3, BaF2, and CuO powders. Transport measurements of the films showed a sharp resistive Tc (R=0) at 89 K and a metallic behavior of resistivity versus temperature. The films show preferred orientations when deposited on single-crystal SrTiO3 substrates (100) or (110) and followed by a post O2 annealing at 825 °C.
Projectile-Charge Dependence Of Ejected-Electron Spectra, V. D. Irby, Timothy J. Gay, J. Wm. Edwards, E. B. Hale, M. L. Mckenzie, R. E. Olson
Projectile-Charge Dependence Of Ejected-Electron Spectra, V. D. Irby, Timothy J. Gay, J. Wm. Edwards, E. B. Hale, M. L. Mckenzie, R. E. Olson
Timothy J. Gay Publications
We have studied H++He and 3He+++He ionizing collisions at intermediate energies (60 to 120 keV/amu) and have observed a significant shift in the velocity position of the maxima in forward-ejected electron spectra when changing projectiles from protons to α particles. In ionizing collisions, a large portion of the ejected electrons are stranded near the transitory equiforce, or saddle point, position between the target ion and receding projectile. The shift in the electron spectra maxima to smaller velocities, due to changing projectiles from protons to α particles, is consistent with the shift in the saddle-point velocity …
Summary Abstract: Formation Of Cr2N Overlayers On A Fe/Cr{110} Crystal, H. Ruppender, M. Grunze, Peter A. Dowben
Summary Abstract: Formation Of Cr2N Overlayers On A Fe/Cr{110} Crystal, H. Ruppender, M. Grunze, Peter A. Dowben
Peter Dowben Publications
In this communication we summarize our experiments related to the formation of chromium surface nitride layers on a Fe72Cr28{110} surface. These surface nitrides were produced by (i) exposure to molecular nitrogen, (ii) exposure to ammonia, and (iii) segregation of nitrogen to the crystal surface. It was found in all cases that the nitrogen concentration in the selvedge scales linearly with the chromium concentration and that chromium segregation is the rate determining step for the formation of a surface nitride.
Oxygen Defect In Yba2Cu3OX: An X-Ray Photoemission Approach, W.K. Ford, C.T. Chen, J. Anderson, J. Kwo, Sy_Hwang Liou, M. Hong, G.V. Rubenacker, J.E. Drumheller
Oxygen Defect In Yba2Cu3OX: An X-Ray Photoemission Approach, W.K. Ford, C.T. Chen, J. Anderson, J. Kwo, Sy_Hwang Liou, M. Hong, G.V. Rubenacker, J.E. Drumheller
Sy-Hwang Liou Publications
A combined x-ray photoemission and diamagnetic-susceptibility study of YBa2Cu3Ox with x≃6 and 7 has been performed, with emphasis on the oxygen defect and the effect of heating in vacuum. By comparing spectra taken at these two oxygen contents, the core levels observed in the O 1s and Ba 4d spectral range are identified. Peak-intensity analysis indicates (1) that the oxygen released during the in situ heating is derived from or near the Cu-O-Cu-O chains of YBa2Cu3O7 and (2) that there is a random distribution of oxygen defects in …
Magnetic Properties Of Rare-Earth Transition-Metal Borides, S.H. Aly, E. Singleton, George C. Hadjipanayis, David J. Sellmyer, Z.R. Zhao
Magnetic Properties Of Rare-Earth Transition-Metal Borides, S.H. Aly, E. Singleton, George C. Hadjipanayis, David J. Sellmyer, Z.R. Zhao
David Sellmyer Publications
The magnetic and structural properties of quaternary RCo4-xFexB alloys with R=Nd, Sm, Er have been examined with magnetometry and x-ray diffraction. The CeCo4B-type phase is found for all x in Er, for x≤3 in Sm, and for x=0, 1, and 2 in Nd. Maximum coercivities have been obtained in a crystallized SmFe2Co2B sample with Hc>17 kOe at room temperature.
Magnetic Properties, Anisotropy, And Microstructure Of Sputtered Rare-Earth Iron Multilayers, Z.S. Shan, S. Nafis, K.D. Aylesworth, David J. Sellmyer
Magnetic Properties, Anisotropy, And Microstructure Of Sputtered Rare-Earth Iron Multilayers, Z.S. Shan, S. Nafis, K.D. Aylesworth, David J. Sellmyer
David Sellmyer Publications
A study of compositionally modulated magnetic films of the form Fe/RE, particularly for RE=Nd and Dy, has been performed by vibrating sample magnetometry, ac susceptibility and x-ray diffraction. The relationship between the magnetic properties and the layer thickness was studied systematically for X-Å Fe/Y-Å Dy, as the layer thicknesses X and Y were varied from 1.8 to 20 Å. The ranges of layer thicknesses required for perpendicular anisotropy were determined. The interface and volume anisotropy energies were estimated for X-Å Fe/Y-Å Nd and the differences in the magnetic properties between X-Å Fe/7-Å Dy and X-Å Fe/7-Å …
Ellipsometric And Magneto-Optic Properties Of Sputtered Dysprosium-Iron Multilayers, Thomas E. Tiwald, John A. Woollam, David J. Sellmyer
Ellipsometric And Magneto-Optic Properties Of Sputtered Dysprosium-Iron Multilayers, Thomas E. Tiwald, John A. Woollam, David J. Sellmyer
David Sellmyer Publications
Ellipsometric and magneto-optical properties of Dy (3.5 Å thick) and Fe (2.5–12.5 Å thick) multilayers were investigated over the spectral range from 3000 to 8000 Å in magnetic fields to 0.21 T. In this range of layer thickness the magnetic anisotropy is vertical. Kerr rotations, were found to be weakly spectrally dependent, and as large as 0.06°. The magnetically driven change of ellipticity of reflected light was as large as 0.13, depending on sample and wavelength. Ellipsometric analysis of layer thickness was performed assuming a multilayer geometry. In addition, the optical constants were determined assuming the multilayer was a homogeneous …
Magnetic Properties Of Rapidly Quenched And Annealed Fe10Rti And Related Alloys, Z.R. Zhao, Y.G. Ren, K.D. Aylesworth, David J. Sellmyer, E. Singleton, J. Strzeszewski, George C. Hadjipanayis
Magnetic Properties Of Rapidly Quenched And Annealed Fe10Rti And Related Alloys, Z.R. Zhao, Y.G. Ren, K.D. Aylesworth, David J. Sellmyer, E. Singleton, J. Strzeszewski, George C. Hadjipanayis
David Sellmyer Publications
Magnetic measurements are reported for iron-rich ternary alloys with the following compositions: Fe10NdxDy1-xTi (0≤x≤1), Fe10SmM (M=Ti, V, and Mo), and Fe10RV (R=Y, Gd, and Dy). The samples were prepared by splat cooling or melt spinning and selected samples were heat treated. The results of x-ray diffraction, electron microscopy, and thermomagnetic measurements on the Fe10NdxDy1-xTi series are presented and indicate that the rapidly quenched alloys are nearly single phase and become multiphase upon heating. Magnetic measurements on the other two series show that the substitution …
Magnetic Transitions And Phases In Random-Anisotropy Magnets, David J. Sellmyer, S. Nafis, Michael J. O'Shea
Magnetic Transitions And Phases In Random-Anisotropy Magnets, David J. Sellmyer, S. Nafis, Michael J. O'Shea
David Sellmyer Publications
The generality and universality of the Ising spin-glass-like phase transitions observed in several rare-earth, random-anisotropy magnets are discussed. Some uncertainties and practical problems in determining critical exponents are considered, and a comparison is made to insulating spin glasses and crystalline spin glasses where an apparent anisotropy-induced crossover from Heisenberg to Ising-like behavior is seen. The observation of a reentrant transition in a weak anisotropy system and its correlation with the theory of Chudnovsky, Saslow, and Serota [Phys. Rev. B 33, 251 (1986)] for the correlated spin glass is discussed. Journal of Applied Physics is copyrighted by The American Institute of …
Particle Size Dependence Of The Magnetic Properties Of Ultrafine Granular Films, Sy_Hwang Liou, C.L. Chien
Particle Size Dependence Of The Magnetic Properties Of Ultrafine Granular Films, Sy_Hwang Liou, C.L. Chien
Sy-Hwang Liou Publications
Magnetic granular solids consist of ultrafine metal granules of nanometer sizes embedded in an insulating medium. The magnetic properties are dictated by the microstructure such as particle size, metal volume fraction, which are process controlled. We report the results of a series of granular Fe60(SiO2)40 films in which the particle size has been systematically varied. The magnetic coercivity, ranging from 500 to 2200 Oe, increases with particle size. The ferromagnetic-superparamagnetic transition had been studied by SQUID magnetometry and Mössbauer spectroscopy. The value of the magnetic anisotropy energy is found to be much larger than that …