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Full-Text Articles in Physics
Lattice-Stiffening Transition In Copolymer Films Of Vinylidene Fluoride (70%) With Trifluoroethylene (30%), C.N. Borca, Shireen Adenwalla, Jaewu Choi, P.T. Sprungerr, Stephen Ducharme, Lee Robertson, S.P. Palto, Jianglai Liu, Matt Poulsen, V.M. Fridkin, H. You, Peter A. Dowben
Lattice-Stiffening Transition In Copolymer Films Of Vinylidene Fluoride (70%) With Trifluoroethylene (30%), C.N. Borca, Shireen Adenwalla, Jaewu Choi, P.T. Sprungerr, Stephen Ducharme, Lee Robertson, S.P. Palto, Jianglai Liu, Matt Poulsen, V.M. Fridkin, H. You, Peter A. Dowben
Peter Dowben Publications
We report the discovery of a compressibility phase transition at 160 K in crystalline copolymer films of vinylidene fluoride ( 70%) with trifluoroethylene ( 30%). This phase transition is distinct from the known bulk ferroelectric-paraelectric phase transition at 353 K and surface ferroelectric phase transition at 295 K. The new phase transition is characterized by an increase in the effective Debye temperature from 48 to 245 K along the 〈010〉 direction as the temperature falls below 160 K. This phase transition is evident in neutron scattering, x-ray diffraction, angle-resolved photoemission, and in the dipole active phonon modes in electron energy-loss …
Selective Adsorption Of Metallocenes On Clean And Chemically Modified Si(111) Surfaces, J.-L. Lin, H. Rauscher, A. Kirakosian, F.J. Himpsel, Peter A. Dowben
Selective Adsorption Of Metallocenes On Clean And Chemically Modified Si(111) Surfaces, J.-L. Lin, H. Rauscher, A. Kirakosian, F.J. Himpsel, Peter A. Dowben
Peter Dowben Publications
Metallocene adsorption on clean Si(111) and CaF2/CaF1/Si(111) substrates has been investigated with scanning tunneling microscopy. The surface chemical composition is found to strongly change the adsorption site selectivity, leading to an enhanced edge selectivity on modified substrates. Templates with well-defined local chemical reactivity have been created via self-assembly. The selective adsorption of metallocenes on such tailored substrates facilitates patterning ordered arrays of magnetic nanowires and stripes on the single digit nanometer scale. ©1999 American Institute of Physics.
Unoccupied Band Structure Of Strained Gadolinium, Takashi Komesu, C. Waldfried, Peter A. Dowben
Unoccupied Band Structure Of Strained Gadolinium, Takashi Komesu, C. Waldfried, Peter A. Dowben
Peter Dowben Publications
From spin-polarized inverse photoemission, the experimental spin-resolved unoccupied band structure of gadolinium on Mo(112) has been constructed. The spin-dependent unoccupied electronic structure near the Fermi level is dominated by shallow dispersion of a spin-minority band. A spin-majority and -minority bulk-band pair also exhibits some dispersion across the Brillouin zone.
Unoccupied Band Structure Of Strained Gadolinium, Takashi Komesu, C. Waldfried, Peter A. Dowben
Unoccupied Band Structure Of Strained Gadolinium, Takashi Komesu, C. Waldfried, Peter A. Dowben
Peter Dowben Publications
From spin-polarized inverse photoemission, the experimental spin-resolved unoccupied band structure of gadolinium on Mo(112) has been constructed. The spin-dependent unoccupied electronic structure near the Fermi level is dominated by shallow dispersion of a spin-minority band. A spin-majority and -minority bulk-band pair also exhibits some dispersion across the Brillouin zone.
Structure And Hysteresis Of Patterned Soft-Magnetic Structure, C. N. Borca, Ralph Skomski, Peter A. Dowben
Structure And Hysteresis Of Patterned Soft-Magnetic Structure, C. N. Borca, Ralph Skomski, Peter A. Dowben
Peter Dowben Publications
We have analyzed the magnetism of Ni features deposited on nonmagnetic substrates using a novel method: laser assisted chemical vapor deposition. Both coercivity and loop shape are determined on a scale of order 1 mm, which is much smaller than the lateral size of the features. The magnetization curves are fitted to a simple substructure morphology model, although there is secondary dependence of the coercivity on the shape of the structures.
The Influence Of Surface Terminal Layer And Surface Defects On The Electronic Structure Of Cmr Perovskites: La0.65A0.35Mno3 (A = Ca, Sr, Ba), Jaewu Choi, Hani Dulli, Sy-Hwang Liou, Peter A. Dowben, Marjorie Langell
The Influence Of Surface Terminal Layer And Surface Defects On The Electronic Structure Of Cmr Perovskites: La0.65A0.35Mno3 (A = Ca, Sr, Ba), Jaewu Choi, Hani Dulli, Sy-Hwang Liou, Peter A. Dowben, Marjorie Langell
Peter Dowben Publications
The electronic structure near to the Fermi level of the colossal magnetoresistance (CMR) perovskite manganite materials, La0.65A0.35MnO3 (A = Ca, Sr, Ba), has been studied using both photoemission and inverse photoemission spectroscopy. The electronic structure for all three materials is very similar and consistent with an Mn–O terminal layer regardless of dopant. Small differences in the electronic structure among the materials are, however, observed. The observed band gap is not significant for La0.65A0.35MnO3 and La0.65A0.35MnO3 while there is a gap, about 1.5 eV, for La …
Evidence Of Dynamic Jahn-Teller Distortions In Two-Dimensional Crystalline Molecular Films, Jaewu Choi, Peter A. Dowben, C.N. Borca, Shireen Adenwalla, A.V. Bune, Stephen Ducharme, V.M. Fridkin, S.P. Palto, N. Petukhova
Evidence Of Dynamic Jahn-Teller Distortions In Two-Dimensional Crystalline Molecular Films, Jaewu Choi, Peter A. Dowben, C.N. Borca, Shireen Adenwalla, A.V. Bune, Stephen Ducharme, V.M. Fridkin, S.P. Palto, N. Petukhova
Peter Dowben Publications
The surface electronic structure in crystalline copolymer films of vinylidene fluoride (70%) with trifluoroethylene (30%) has been studied by photoemission and inverse photoemission as a function of alkali metal (sodium) doping. Sodium doping introduces at least two new states into the band (HOMO-LUMO) gap well away from the Fermi level. While the sodium-doped copolymer is observed to resemble an n-type semiconductor, the change in electronic structure with temperature suggests that dynamic distortions lead to a photoemission initial state splitting of the lower Hubbard-like bands. There is a decrease in the effective Debye temperature with sodium doping which may, in turn, …
Structural Domain Growth Of Strained Gadolinium On Mo(112), C. Waldfried, Peter A. Dowben, O. Zeybek, T. Bertrams, S. D. Barrett
Structural Domain Growth Of Strained Gadolinium On Mo(112), C. Waldfried, Peter A. Dowben, O. Zeybek, T. Bertrams, S. D. Barrett
Peter Dowben Publications
The growth mode of domains of the hexagonal lattice of strained gadolinium deposited on Mo(112) has been investigated with low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM). The molybdenum substrate corrugations and the expansive strain within the gadolinium films dominate the growth of the thin Gd films, which is characterized by a preferential domain growth direction of the hexagonal Gd crystal structure, unlike the more uniform, epitaxial growth of ‘unstrained’ gadolinium, grown on W(110).