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Full-Text Articles in Physics

Selective Area Deposition Of Conducting Palladium Films On Polyimide Resins, Yoon-Gi Kim, S. Bialy, R.W. Miller, J.T. Spencer, Peter A. Dowben, Saswati Datta May 1990

Selective Area Deposition Of Conducting Palladium Films On Polyimide Resins, Yoon-Gi Kim, S. Bialy, R.W. Miller, J.T. Spencer, Peter A. Dowben, Saswati Datta

Peter Dowben Publications

We have demonstrated that the selective area deposition of palladium on polyimide substrates i s possible through the U.V. photolysis of (π - a l l y 1) (π –cyclopentadieny1) palladium. This photolytic deposition process did not result in any apparent damage to either the Ultem 1000 (polyetherimide) or Kapton substrates (polyimide substrates). The resistivity of the palladium films (< 0.1 um) suggests that the films are porous.


Magnetic Ordering Of Tb Overlayers On Ni(Ll1), D. Lagraffe, A. Miller, Peter A. Dowben, M. Onellion May 1990

Magnetic Ordering Of Tb Overlayers On Ni(Ll1), D. Lagraffe, A. Miller, Peter A. Dowben, M. Onellion

Peter Dowben Publications

The 5p3/2 to 5p1/2 shallow core level branching ratios in different - photoemission geometries provide a measure of the magnetic ordering in rare earth overlayers as a result of final state effects in photoemission. This 5p level anisotropy can be used to probe magnetic ordering across the Tb Curie temperature as well as magnetic ordering induced by a ferromagnetic substrate in Results are shown for paramagnetic Tb overlayers on Ni(111). The Ginsberg-Landau theory can be used to accurately model terbium thin films for T>Tc.


Magnetic And Structural Properties Of High-Coercivity Pr2Fe14Bpr Cosputtered Films, K.D. Aylesworth, David J. Sellmyer, George C. Hadjipanayis May 1990

Magnetic And Structural Properties Of High-Coercivity Pr2Fe14Bpr Cosputtered Films, K.D. Aylesworth, David J. Sellmyer, George C. Hadjipanayis

David Sellmyer Publications

The results of structural and magnetic measurements on a series of films produced by cosputtering Pr21Fe72B7 and Pr are reported. The materials were deposited serially, 10–200 Å at a time, onto 700 °C Ta substrates attached to a computer-controlled stepping motor. The structure of the resulting films was examined by large- and small-angle x-ray diffraction, scanning electron microscopy, and by microprobe analysis. Magnetic measurements were made at temperatures from 4.2 to 300 K, in fields up to 80 kOe in a vibrating sample magnetometer. The films appear to consist of 1-µm grains of Pr2 …


Enhancement Of Magneto-Optical Kerr Effects, Liang-Yao Chen, William A. Mcgahan, Z.S. Shan, David J. Sellmyer, John A. Woollam May 1990

Enhancement Of Magneto-Optical Kerr Effects, Liang-Yao Chen, William A. Mcgahan, Z.S. Shan, David J. Sellmyer, John A. Woollam

David Sellmyer Publications

A general expression for the magneto-optical polar Kerr effect is given for a bilayered configuration in which the optical constants of the two media differ. The equation shows that a giant enhancement of the Kerr effect in magneto-optical/metallic bilayers can be expected if the dielectric constants of the two materials are low or are matched well to the other. An explicit equation is also given to calculate the spectral enhancement due to a dielectric overcoating on magnetic substrates. An example is given for SiO-coated Dy/Co compositionally modulated alloys, yielding a good comparison to the experimental results in both the transparent …


Magnetic And Structural Studies In Sm-Fe-Ti Magnets, Y. Wang, George C. Hadjipanayis, A. Kim, N.C. Liu, David J. Sellmyer May 1990

Magnetic And Structural Studies In Sm-Fe-Ti Magnets, Y. Wang, George C. Hadjipanayis, A. Kim, N.C. Liu, David J. Sellmyer

David Sellmyer Publications

The effects of vanadium substitution on the magnetic properties of Sm-Fe-Ti-V melt-spun ribbons and the magnetic properties and microstructure of sintered Sm-Fe-Ti based magnets are reported. The highest coercivity, Hc =10.65 kOe, was obtained in a heat-treated melt-spun Sm8 Fe75.5 Ga0.5 Ti8 V8 alloy. This is the highest value of the coercivities reported in alloys with the ThMn12 -type structure. Bulk magnets were prepared by the usual powder metallurgy technique. However, their highest coercivity (~2 kOe) was much less than that of the corresponding ribbons. The low coercivity of sintered magnets has been …


Electronic Structure And Magnetic Properties Of Fe-Rich Ternary Compounds: Yfe10V2 And Yfe10Cr2, Sitaram Jaswal, Y.G. Ren, David J. Sellmyer May 1990

Electronic Structure And Magnetic Properties Of Fe-Rich Ternary Compounds: Yfe10V2 And Yfe10Cr2, Sitaram Jaswal, Y.G. Ren, David J. Sellmyer

David Sellmyer Publications

These compounds are prototypes of the Fe-rich ternary systems of ThMn12 structure which are of considerable current interest as permanent magnet materials. The electronic structure of YFe10V2 and YFe10Cr2 have been studied with photoemission and spin-polarized calculations. The Fe d states dominate the calculated density of states (DOS) near the Fermi energy and there is a good correspondence between the DOS and the experimental spectra. The calculated magnetization is in very good agreement with the experimental data. The calculations give a magnetic moment of ~1 µB at the V or Cr site …


An Analytic Representation Of The Radial Distribution Of Dose From Energetic Heavy Ions In Water, Si, Lif, Nai, And Sio2, Robert Katz, Kim Sum Loh, Luo Baling, Guo-Rong Huang May 1990

An Analytic Representation Of The Radial Distribution Of Dose From Energetic Heavy Ions In Water, Si, Lif, Nai, And Sio2, Robert Katz, Kim Sum Loh, Luo Baling, Guo-Rong Huang

Robert Katz Publications

An earlier representation of the radial distribution of dose about the path of a heavy ion in liquid water is modified and extended to include silicon, lithium fluoride, sodium iodide, and silicon dioxide.


Variational Methods For High-Order Multiphoton Processes, Bo Gao, Cheng Pan, Chih-Ray Liu, Anthony F. Starace Apr 1990

Variational Methods For High-Order Multiphoton Processes, Bo Gao, Cheng Pan, Chih-Ray Liu, Anthony F. Starace

Anthony F. Starace Publications

Methods for applying the variationally stable procedure for N th-order perturbative transition matrix elements of Gao and Starace [Phys. Rev. Lett. 61, 404 (1988); Phys. Rev. A 39, 4550 (1989)] to multiphoton processes involving systems other than atomic H are presented. Three specific cases are discussed: one-electron ions or atoms in which the electron-ion interaction is described by a central potential; two-electron ions or atoms in which the electronic states are described by the adiabatic hyperspherical representation; and closed-shell ions or atoms in which the electronic states are described by the multiconfiguration Hartree-Fock representation. Applications are made to the dynamic …


First-Principles Simulations Of Ionic Molecular Solids: The Phase Transitions In K2Seo4, H. M. Lu, John R. Hardy Feb 1990

First-Principles Simulations Of Ionic Molecular Solids: The Phase Transitions In K2Seo4, H. M. Lu, John R. Hardy

John R. Hardy Papers

We present a new approach to first-principles simulations of the statics and dynamics of ionic molecular crystals. It is shown that the new method gives very realistic simulations of the phase transitions in K2SeO4 and that a double-well type of structure in the potential-energy surface is the driving mechanism of these phase transitions.


Cross Section, Robert Katz Jan 1990

Cross Section, Robert Katz

Robert Katz Publications

In radiobiology the term cross section is used in ways that depart from its original physical meaning. Some of these conceptual extensions represent significant distortions of the original concept. These distortions lead to the misinterpretation of experimental findings.


Near-100% Production Of The Excited Be+ 1s22p Ion From Decay Of Be 1s2S22p, C. Denise Caldwell, Mark G. Flemming, Manfred O. Krause, Peter Van Der Meulen, Cheng Pan, Anthony F. Starace Jan 1990

Near-100% Production Of The Excited Be+ 1s22p Ion From Decay Of Be 1s2S22p, C. Denise Caldwell, Mark G. Flemming, Manfred O. Krause, Peter Van Der Meulen, Cheng Pan, Anthony F. Starace

Anthony F. Starace Publications

In examining the decay of photon-produced Be 1s2s2np(1P), n=2,3, we discovered that the vastly predominant decay mode is to the final excited ionic states Be+ 1s2np, rather than the ground state. For n=2, the 2p ion accounts for 95% of the total production, with Be+ 1s23p the other main contributor. For n=3, 3p is predominant, again with a very small fraction of 2s. The result for n=2 occurs as a consequence of the similarity between the 2s and …