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Full-Text Articles in Engineering
Impact Of Symmetry On The Ferroelectric Properties Of Catio₃ Thin Films, Michael D. Biegalski, Liang Qiao, Yijia Gu, Apurva Mehta, Qian He, For Full List Of Authors, See Publisher's Website.
Impact Of Symmetry On The Ferroelectric Properties Of Catio₃ Thin Films, Michael D. Biegalski, Liang Qiao, Yijia Gu, Apurva Mehta, Qian He, For Full List Of Authors, See Publisher's Website.
Materials Science and Engineering Faculty Research & Creative Works
Epitaxial strain is a powerful tool to induce functional properties such as ferroelectricity in thin films of materials that do not possess ferroelectricity in bulk form. In this work, a ferroelectric state was stabilized in thin films of the incipient ferroelectric, CaTiO3, through the careful control of the biaxial strain state and TiO6 octahedral rotations. Detailed structural characterization was carried out by synchrotron x-ray diffraction and scanning transmission electron microscopy. CaTiO3 films grown on La0.18Sr0.82Al0.59Ta0.41O3 (LSAT) and NdGaO3 (NGO) substrates experienced a 1.1% biaxial strain state …
In-Plane Anisotropy And Temperature Dependence Of Oxygen Phonon Modes In Yba₂Cu₃O₆.₉₅, Jaeho Chung, Takeshi Egami, R. J. Mcqueeney, Mohana Yethiraj, Masatoshi Arai, Tetsuya Yokoo, Yu Nikolaijevitsch Petrov, Herbert A. Mook, Yasuo Endoh, Setsuko Tajima, Christopher D. Frost, Fatih Dogan
In-Plane Anisotropy And Temperature Dependence Of Oxygen Phonon Modes In Yba₂Cu₃O₆.₉₅, Jaeho Chung, Takeshi Egami, R. J. Mcqueeney, Mohana Yethiraj, Masatoshi Arai, Tetsuya Yokoo, Yu Nikolaijevitsch Petrov, Herbert A. Mook, Yasuo Endoh, Setsuko Tajima, Christopher D. Frost, Fatih Dogan
Materials Science and Engineering Faculty Research & Creative Works
Inelastic pulsed neutron scattering measurements on YBa2Cu3O6.95 single crystals indicate that the sample has a distinct a-b plane anisotropy in the oxygen vibrations. The Cu-O bond-stretching-type phonons, which are suspected to interact strongly with charge, are simultaneously observed along the a and b directions due to a 7-meV splitting arising from the orthorhombicity, even though the sample is twinned. The bond-stretching LO branch with the polarization along a (perpendicular to the chain) loses intensity beyond the middle of the zone, indicating branch splitting as seen in doped nickelates, with the second branch being located at …
Magnetic Order In Yba₂Cu₃O₆₊ₓ Superconductors, Herbert A. Mook, Pengcheng Dai, Stephen M. Hayden, Arno Hiess, Jeffrey W. Lynn, Seunghun Lee, Fatih Dogan
Magnetic Order In Yba₂Cu₃O₆₊ₓ Superconductors, Herbert A. Mook, Pengcheng Dai, Stephen M. Hayden, Arno Hiess, Jeffrey W. Lynn, Seunghun Lee, Fatih Dogan
Materials Science and Engineering Faculty Research & Creative Works
Polarized and unpolarized neutron diffraction has been used to search for magnetic order in YBa2Cu3O6+x superconductors. Most of the measurements were made on a high quality crystal of YBa2CU3O6.6. It is shown that this crystal has highly ordered ortho-II chain order, and a sharp superconducting transition. Inelastic scattering measurements display a very clean spin-gap and pseudogap with any intensity at 10 meV being 50 times smaller than the resonance intensity. The crystal shows a complicated magnetic order that appears to have three components. A magnetic phase is found at …
Observation Of Changes In The Atomic And Electronic Structure Of Single-Crystal Yba₂Cu₃O₆.₆ Accompanying Bromination, Lamine M. Dieng, Yasuhiro Inamura, Trevor A. Tyson, Mark C. Croft, Fatih Dogan, C. Y. Kim, Joseph C. Woicik, James M. Grow
Observation Of Changes In The Atomic And Electronic Structure Of Single-Crystal Yba₂Cu₃O₆.₆ Accompanying Bromination, Lamine M. Dieng, Yasuhiro Inamura, Trevor A. Tyson, Mark C. Croft, Fatih Dogan, C. Y. Kim, Joseph C. Woicik, James M. Grow
Materials Science and Engineering Faculty Research & Creative Works
To ascertain the role of bromination in the recovery of superconductivity in underdoped YBa2Cu3O6+y (YBCO), we have performed polarized multiple-edge x-ray-absorption fine structure (XAFS) measurements on normal (y~0.6) and brominated (Br/Cu~1/30, y~0.6) single crystals with superconducting transitions at 63 and 89 K, respectively. The brominated sample becomes strongly heterogeneous on an atomic length scale. Approximately one-third of YBCO is locally decomposed yet incorporated as a well-ordered "host" lattice as nanoscale regions. The decomposed phase consists of heavily distorted domains with an order not following that of the "host" lattice. Structurally, these domains are fragments of …
Evolution Of The Resonance And Incommensurate Spin Fluctuations In Superconducting Yba₂Cu₃O₆₊ₓ, Pengcheng Dai, Herbert A. Mook, Rodney Dale Hunt, Fatih Dogan
Evolution Of The Resonance And Incommensurate Spin Fluctuations In Superconducting Yba₂Cu₃O₆₊ₓ, Pengcheng Dai, Herbert A. Mook, Rodney Dale Hunt, Fatih Dogan
Materials Science and Engineering Faculty Research & Creative Works
Polarized and unpolarized neutron triple-axis spectrometry was used to study the dynamical magnetic susceptibility Χ″(q, ω) as a function of energy (ℏ ω) and wave vector (q) in a wide temperature range for the bilayer superconductor YBa2Cu3O6+x with oxygen concentrations, x, of 0.45, 0.5, 0.6, 0.7, 0.8, 0.93, and 0.95. The most prominent features in the magnetic spectra include a spin gap in the superconducting state, a pseudogap in the normal state, the much-discussed resonance, and incommensurate spin fluctuations below the resonance. We establish the doping dependence of the spin gap in the superconducting state, …
Mixed Electron Emission From Lead Zirconate-Titanate Ceramics, Weiming Zhang, Wayne Huebner, Stephen E. Sampayan, Mike L. Krogh
Mixed Electron Emission From Lead Zirconate-Titanate Ceramics, Weiming Zhang, Wayne Huebner, Stephen E. Sampayan, Mike L. Krogh
Materials Science and Engineering Faculty Research & Creative Works
Simultaneous ferroelectric and plasma emission from Pb(Zr,Ti)O3 was observed with only a negative driving pulse applied to the sample, and without an extraction potential on the electron collector. Plasma emission was a strong, inconsistent, and self-destructive process. In addition, a positive ion current was detected. Comparatively, ferroelectric emission was a relatively stable self-emission process, exhibiting no apparent delay time, and no positive ion current. The relationship between the switching and emission current of ferroelectric samples measured simultaneously cannot only be used to determine the existence of ferroelectric emission, but can also give direction to choosing suitable ferroelectric materials for …
Magnetic Dynamics In Underdoped Yba₂Cu₃O₇₋ₓ: Direct Observation Of A Superconducting Gap, Pengcheng Dai, Mohana Yethiraj, Herbert A. Mook, Terrence B. Lindemer, Fatih Dogan
Magnetic Dynamics In Underdoped Yba₂Cu₃O₇₋ₓ: Direct Observation Of A Superconducting Gap, Pengcheng Dai, Mohana Yethiraj, Herbert A. Mook, Terrence B. Lindemer, Fatih Dogan
Materials Science and Engineering Faculty Research & Creative Works
Polarized and unpolarized triple-axis neutron measurements were performed on an underdoped crystal of YBa2Cu3O7-x (x = 0.4 ± 0.02, Tc = 62.7 K). Our results indicate, contrary to earlier evidence, that the spin excitations in the superconducting state are essentially the same as those in the fully doped material except that the unusual 41 meV resonance is observed at 34.8 meV. The normal state spin excitations are characterized by a weakly energy-dependent continuum whose temperature dependence shows the clear signature of a superconducting gap at Tc. The enhancement at the resonance is …
Thermally Stimulated Polarization Current Technique For Measuring The Electrical Conductivity Of Vitreous Solids, Chi-Ming Hong, D. E. Day
Thermally Stimulated Polarization Current Technique For Measuring The Electrical Conductivity Of Vitreous Solids, Chi-Ming Hong, D. E. Day
Materials Science and Engineering Faculty Research & Creative Works
The electrical conductivity of glasses determined by TSPC agrees well with that measured by conventional ac or dc techniques. The TSPC technique is a rapid and easy method of measuring the dc conductivity over the range 10−15-10−7 (Ω cm)−1 and is especially suited for conductivities <10−12 (Ω cm)−1. Polarization at the electrodes is easily detected and avoided.