Giles Smith, C. E. Emmett, Andrew Robson, Janice Turner, Phil Yates, Christina Hardyment, Susie Stoddart, Bruce Campbell, Griselda Greaves, John McNamara, Andrew Eames, Stella Shamoon, Robert Cole, Bel Mooney, Joanna Bale and Richard Ford, David Canter, Martin Peters and Frank Lampard, Patricia Davies, Janie Turner, Ian Nathan, Sarah vine, Jane MacQuitty, Simon Barnes, Peter Lansley, Jill Hartley, Tom Baldwin and Christine Selb, Robert Thicknesse, Duncan Grey, Dunhill Links Championship, Jan Morris, Paul Hoggart, Christopher Wood, Mark Souster, John Mulvey, Ian MacKinnon and Stephen Farrell, Anthony Lloyd, Nick Hawton, Clare Lazaro, Spiros Politis, Matt Wolf, Philip Howard, Richard Beard, Carol Midgley, Mark Hudson President, David Chater, Jonathan Meades's, Michael Binyon, Joanna Bale, James Bone, Jane Goldman, Dominic Wells, Clive Davis, Kate Reardon, Anne Gatti, Sheila Johnston, Monica Porter, Lucia Van Der Post, Bob Stanley, Martin Aston, Sam Marlowe, Paul McNamee, Wendy Ide, Stuart Miles, Tim Wapshott and Dominic Wells, John Bungey, Kevin Eason, Peter Barlow, Geoff Brown, Clare Stewart, Giles Coren, Andrew Norfolk, Rosie Millard, Alastair Campbell, Antonia Senior, Nancy Durrant, Valerie Elliott Countryside Editor, David McVay, John Clarke, Stephen McClarence, Hilary Rose, Vinny Lee, Rob Cassy, MG, Henrietta Green, John Hopkins, Golf Correspondent, Katherine Swift, Ernie Els, Dominic Walsh, Tania Alexander, James Doran Wall Street Correspondent, Debra Craine, Shirley English, Eric Hulse, Gary Jacob, Hilary Weale, Greg Watts, Joe Morgan, Grainne Gilmore, Tim Reid, Daniel Finkelstein, P. 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Nethercoat, Christine Buckley, Suzi Godson, Lewis Smith, Sean MacAulay, Fiona Morrow, Richard Brass, Gordon Ramsay, Christine Buckley Industrial Editor, Allan Leighton, Abigall Rayner, Bronwen Maddox, Helen Rumbelow Political Correspondent, Jens Lexman, Patrick Hosking, Peter Allam, Mark Irving, Alex Hawkes, Mick Hume, Gareth Child, Jeremy Das, Emily Davies, Fred Dellar, Peter Dixon, James Naughtie, Isabel Conway and Daniel McGrory, Clive David, Dalya Alberge, David Hands Rugby Correspondent, Julian Muscat, Colin Liddell, Adam Fresco, Mike Mulvihill, Peter Allies, Ray Gosling, Nigel Kendall, Nick Szczepanik, John Goodbody, Joanna Pitman, Maureen Shaw, Philip Webster Political Editor, Jonathan Clayton, Stefanle Marsh, Robert Crampton, Jane Shilling, Peter Inson Headmaster, Craig Lord, Mel Webb, Ian Johns, Ben Webster Transport Correspondent and Jenny Davey, Neville Denson, Matthew Parris, William Boyd, George Caulkin, Jonathan Rendall, John Lister-Kaye, Sam McKnight, Caitlin Moran, Rebecca Ley, Sheila Keating, Neil Fisher, Abigall Rayner and Tom Bawden, Iain Finlayson, Michael Collins, Ben MacIntyre, Helen Pridham, Ron Sirak, Richard Beeston, Brian Glanville, C.w.w. Eastbourne, Richard Beeston Diplomatic Editor, Denis Seguin, Alison Gibson, David Sanderson, John Naish, Anne Ashworth Personal Finance Editor, Annabelle Thorpe, Martin Waller, Mark Henderson, Michael Horsnell, Chris Ayres, Mark Cocker, Tom Bawden and Sarah Butler, Laura Peek, Sarah Butler, Ashling O'Connor, Benedict Nightingale, Oliver Kamm, Darian Leader, Mel Webbb, Dr Thomas Stuttaford, Allan Mann, Jill Crawshaw, Stephen Dalton, Anna-Marie Crowhurst, Alyson Rudd, Bill Edgar, Tom Chesshyre, Paul Connolly, James Christopher, Hal St John Broadbent, Deb Atkinson, Lucy Broadbent, Kelly Hoppen, Simon Crompton, Alan Lee Racing Correspondent, Alan Jackson, Owen Slot, Alexander W. MacAra, Susannah Jowitt, Cath Urquhart Travel Editor, Rachel Campbell-Johston, Christopher Jackson, Jenny Davey, Douglas Kennedy, Peter Klinger, Sam Lister Health Correspondent, Patience Wheatcroft, Joe Bolger, Philip Webster, Daniel McGrory and James Hider, Christopher Irvine, Rick Lew, Chloe Bryan-Brown,
... Herbs Picture Gallery Pictureline The Listener Crossword No 3795 Koeql Haeospo by Elgin Bridge Word Watching Two ... Campbell is back, this time as Elvis, says Nigel Kendall DVD Reviews Little Britain is a national ...
2004 - Gale Group | TDA
Mingfu Guan, Nigel Wright, P.A. Sleigh,
SUMMARY A robust Godunov‐type numerical scheme solver is proposed for solving 2D SWEs and is applied to simulate flow over complex topography with wetting and drying. In reality, the topography is usually complex and irregular; therefore, to avoid the numerical errors generated by such features, a Homogenous Flux Method is used to handle the bed slope term in the SWEs. The method treats the bed slope term as a flux to be incorporated into the flux gradient and so maintains the balance between the ...
Tópico(s): Advanced Numerical Methods in Computational Mathematics
2013 - Wiley | International Journal for Numerical Methods in Fluids
Giles Smith, Andrew Robson, Lucy Alexander, Gabriele Marcotti, Richard Whitehead, Andrew Pierce, Catherine Ashton, Sarah Potter, Gary Duncan, lan Whittell, Peter Lansley, Paul Hoggart, James Hidler and Daniel McGrory, Dr Paul D. Oldfield, Philip Howard, Hilary Finch, Michael Simkins, Suna Erdem, Joanna Bale, James Bone, Sebastian Saville, Alexandra Frean Social Affairs Correspondent, Carol Sarler, Richard Irving, Will Pavia, Roger Maynard, Geoff Brown, Greg Hurst and Andrew Pierce, Sam Lister, Joe Joseph, David McVay, Donald Hutera, Ben Webster and joanna Bale, David Nicolson, Ruth Gledhill, Dominic Walsh, Debra Craine, Gary Jacob, Joe Morgan, Jill Dupleix, Professor Ian Fells, David Crane, Alan Coombes, Tim Buzaglo, Phil Gordon, Keith Pike, Bop Balchin, David Hands, Dr Monika S. Schmid, Ron Lewis, Ian MacKinnon, Anthony Aust, Liz Chong, Alex Coronation, Greg Hurst, John M. Paterson, Russell Kempson, Gary Duncan Economics Editor, Oliver Kay, Guy Whittingham, Sarah Vine, Dr W. S. Affleck, John Westerby, Neil Harman, Rick Broadbent, Christopher Martin-Jenkins, John Hopkins Golf Correspondent, Gabriel Rozenberg, David Powell Athletics Correspondent, Adam Sage, Lewis Smith, Matthew Pryor, Peter Riddell Political Briefing, Matt Dickinson, Matt Hughes, Mark Atkins, Rosemary Bennet Deputy Political Editor, Cliff Prior, Kaveh Solhekol, Nigel Hawkes, Chris Campling, Cathy Harris, Patrick Hosking, Richard Owen, Nigel Mobbs, Damian Whitworth, Roger Boyes, Peter Dixon, Gabriel Rozenberg Economics Reporter, John Ebbrell, Geoff Griffiths, Andrew Jack, David Hands Rugby Correspondent, Tom Dart, Julian Muscat, Melissa Fleming, William Rees-Mogg, Dominic Kennedy, Mel Webb, Ashling O'connor, Adam MacQueen, Anjana Ahuja, George Caulkin, Caitlin Moran, Tim Martin, Graham Brady, Allen Robertson, Keith Vaz, Mp, Tim Hall, Martin Waller, Christopher Irvine, Chris Ayres, James Jackson, Danny Baker, Mark Baldwin, Sarah Butler, Lewis Smith and Russel Jenkins, Benedict Nightingale, Dr Ian Davis, Dr Thomas Stuttaford, Stephen Dalton, Leo Lewis, David Powell, Bill Edgar, Geoff Watson, Adam Sherwin, Michael Evans, Mark Venables, Thomas Stuttaford, Gerard Baker us Editor, Dan McDougall,
... Cubed The Times times2 Quiz times2 Crossword No 3795 Word Watching Polygon The Writers Bureau College of ...
2006 - Gale Group | TDA
M. B. Salamon, S. E. Inderhees, J. P. Rice, B. G. Pazol, D. M. Ginsberg, Nigel Goldenfeld,
In a $c$-axis magnetic field, the specific-heat peak of a single crystal of $\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ broadens and decreases in amplitude with little shift in position. The difference between the zero-field specific heat and that measured in a field is found to satisfy a scaling relation which suggests critical, as opposed to Gaussian, fluctuations. This is interpreted in terms of the broadening of the critical regime by the magnetic ...
Tópico(s): Theoretical and Computational Physics
1988 - American Physical Society | Physical review. B, Condensed matter
P. J. Hirschfeld, Nigel Goldenfeld,
For a pure superconductor in a d-wave-like state at temperatures T well below the critical temperature ${\mathit{T}}_{\mathit{c}}$, the deviation \ensuremath{\Delta}\ensuremath{\lambda} of the penetration depth from its zero-temperature value \ensuremath{\lambda}(0) is proportional to T. When the concentration ${\mathit{n}}_{\mathit{i}}$ of strongly scattering impurities is nonzero, \ensuremath{\Delta}\ensuremath{\lambda}\ensuremath{\propto}${\mathit{T}}^{\mathit{n}}$, where n=2 for T${\mathit{T}}^{\mathrm{*}}$\ ...
Tópico(s): Advanced Condensed Matter Physics
1993 - American Physical Society | Physical review. B, Condensed matter
I. M. Ruzin, Nigel R. Cooper, Bertrand I. Halperin,
We show that, at low temperatures, macroscopic inhomogeneities of the electron density in the interior of a finite sample cause a reduction in the measured conductivity peak heights ${\mathrm{\ensuremath{\sigma}}}_{\mathit{xx}}^{\mathrm{max}}$ compared to the universal values previously predicted for infinite homogeneous samples. This effect is expected to occur for the conductivity peaks measured in standard experimental geometries such as the Hall bar and the Corbino disk. At the lowest temperatures, ...
Tópico(s): Surface and Thin Film Phenomena
1996 - American Physical Society | Physical review. B, Condensed matter
Sudhanshu Shukla, M. Shayegan, S. R. Parihar, S. A. Lyon, Nigel R. Cooper, A. A. Kiselev,
We report tilted-field magnetotransport measurements of two-dimensional electron systems in a 200 Angstrom-wide Al(0.13)Ga(0.87)As quantum well. We extract the energy gap for the quantum Hall state at Landau level filling \nu =1 as a function of the tilt angle. The relatively small effective Lande g-factor (g ~ 0.043) of the structure leads to skyrmionic excitations composed of the largest number of spins yet reported (s ~ 50). Although consistent with the skyrmion size observed, Hartree-Fock calculations, ...
Tópico(s): Physics of Superconductivity and Magnetism
2000 - American Physical Society | Physical review. B, Condensed matter
Nigel R. Cooper, N. K. Wilkin,
We study the properties of rotating Bose-Einstein condensates in parabolic traps, with coherence length large compared to the system size. In this limit, it has been shown that unusual groundstates form which cannot be understood within a conventional many-vortex picture. Using comparisons with exact numerical results, we show that these groundstates can be well-described by a model of non-interacting ``composite fermions''. Our work emphasises the similarities between the novel states that appear ...
Tópico(s): Physics of Superconductivity and Magnetism
1999 - American Physical Society | Physical review. B, Condensed matter
Robert F. Klie, Marco Beleggia, Yuntian Zhu, J. P. Buban, Nigel D. Browning,
A combination of experiments and theoretical calculations is used to develop an atomic-scale model of the grain boundary potential in perovskite oxides. More specifically, pristine $8\ifmmode^\circ\else\textdegree\fi{}$ and $58\ifmmode^\circ\else\textdegree\fi{}$ $[001]$ tilt grain boundaries in ${\mathrm{SrTiO}}_{3},$ which can be regarded as model systems for all cubic perovskite systems, are examined by Z-contrast imaging and electron-energy-loss spectroscopy. Based on results obtained from these systems, ...
Tópico(s): Magnetic and transport properties of perovskites and related materials
2003 - American Physical Society | Physical review. B, Condensed matter
We study the charged excitations of quantum Hall systems at integer filling fractions \ensuremath{\nu}=2n+1, for a force law that takes account of the finite width of the electron gas. For typical values of this width, in the limit of vanishing Zeeman energy we find that the low-energy excitations are skyrmions not only at \ensuremath{\nu}=1 but also at higher filling fractions. Our results lead to the prediction that, in typical samples, abrupt transitions to charged excitations with very large spins ...
Tópico(s): Physics of Superconductivity and Magnetism
1997 - American Physical Society | Physical review. B, Condensed matter
Jin‐Tae Kim, Nigel Goldenfeld, J. Giapintzakis, D. M. Ginsberg,
The in-plane longitudinal resistivities ${\ensuremath{\rho}}_{\mathrm{aa}}$ and ${\ensuremath{\rho}}_{\mathrm{bb}}$ of a single-crystal of ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ have been measured as a function of magnetic field $H$ (less than 6.75 T) and temperature $T$ near ${T}_{c}.$ We found that the ${\ensuremath{\rho}}_{\mathrm{aa}}(T,H)$ data in the mixed state collapse into a single curve as a function of ${\ensuremath{\rho}}_{\mathrm{bb}}(T, ...
Tópico(s): Theoretical and Computational Physics
1997 - American Physical Society | Physical review. B, Condensed matter
Keith M. Murdoch, Nigel J. Cockroft,
The property of preferential pair formation for trivalant ions in ${\mathrm{CsCdBr}}_{3}$ has been utilized to isolate and investigate energy cross-relaxation and upconversion processes of thulium and praseodymium. The principal pair centers formed by ${\mathrm{Tm}}^{3+}$ and ${\mathrm{Pr}}^{3+}$ ions in ${\mathrm{CsCdBr}}_{3}$ have been identified, including the heterogeneous ${\mathrm{Tm}}^{3+}$-${\mathrm{Pr}}^{3+}$ pair center. Their energy levels and fluorescence lifetimes have been measured at 10 K. Many ...
Tópico(s): Advanced Condensed Matter Physics
1996 - American Physical Society | Physical review. B, Condensed matter
A transferable empirical potential for carbon is developed by extending the environment-dependent interaction potential proposed for silicon. Generalized coordination functions, parametrized using ab initio data, describe dihedral rotation, nonbonded $\ensuremath{\pi}$-repulsion and fractional coordination. Elastic constants agree well with experiment, and simulations of liquid carbon compare very favorably with Car-Parrinello calculations. Amorphous networks generated by liquid quench have properties ...
Tópico(s): Material Dynamics and Properties
2000 - American Physical Society | Physical review. B, Condensed matter
Nigel J. Cockroft, Steven H. Lee, John C. Wright,
${\mathrm{Eu}}^{3+}$-doped ${\mathrm{SrTiO}}_{3}$, ${\mathrm{Sr}}_{2}$${\mathrm{TiO}}_{4}$, ${\mathrm{Sr}}_{3}$${\mathrm{Ti}}_{2}$${\mathrm{O}}_{7}$, and ${\mathrm{Sr}}_{4}$${\mathrm{Ti}}_{3}$${\mathrm{O}}_{10}$ phases have been studied by site-selective laser spectroscopy. The spectra of the dominant sites have been identified and assigned to ${\mathrm{Eu}}^{3+}$ substitution on Sr sites with distant charge compensation. The spectra of nonstoichiometric samples show that the nonstoichiometry is accommodated by ...
Tópico(s): Magnetic and transport properties of perovskites and related materials
1991 - American Physical Society | Physical review. B, Condensed matter
The molecular-dynamics technique involving the rapid cooling of a liquid to simulate an amorphous solid has been used for several years. Despite the success of the technique, the method has lacked a physical justification, and the cooling rates have been assumed to be too fast. In this paper an analysis of thermal spike cooling times in tetrahedral amorphous carbon shows that the method is reasonable and that rapid cooling rates are appropriate. Using three independent methods it is found that the ...
Tópico(s): High-pressure geophysics and materials
1997 - American Physical Society | Physical review. B, Condensed matter
Margaret Cupples, Judith Cole, Nigel Hart, Neil Heron, Michelle C. McKinley, Mark A. Tully,
Effective interventions are needed to support health behaviour change for cardiovascular disease (CVD) prevention. Decision tools encourage behaviour change but their effectiveness when used in shared decision-making with health professionals (HPs) is unknown.To test the feasibility of using a novel, paper-based tool for shared decision-making in initiating behaviour change.A feasibility study in five general practices in Northern Ireland.Adults with, or at high risk of, CVD were invited to discuss ...
Tópico(s): Health Literacy and Information Accessibility
2018 - Royal College of General Practitioners | BJGP Open
Markus P. Hehlen, Nigel J. Cockroft, T. R. Gosnell, A.J. Bruce,
A spectroscopic investigation of an extensive series of ${\mathrm{Er}}^{3+}$-doped and ${\mathrm{Er}}^{3+}{,\mathrm{Y}\mathrm{b}}^{3+}$-codoped soda-lime-silicate (SL) and aluminosilicate (AS) glasses is presented. Compared to SL glasses, $4f$ transitions in AS glasses show higher oscillator strengths, larger inhomogeneous broadening, and smaller crystal-field splittings of the respective excited-state multiplets. The ${\mathrm{Er}}^{3+}$ excited-state relaxation dynamics is adequately described by a combination ...
Tópico(s): Lanthanide and Transition Metal Complexes
1997 - American Physical Society | Physical review. B, Condensed matter
James F. Annett, Nigel Goldenfeld, S. R. Renn,
The low-temperature behavior of the a-b plane penetration depth, ${\ensuremath{\lambda}}_{\mathit{a}\mathit{b}}$, is a probe of the pairing state in ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$. A group-theoretic analysis shows that in orthorhombic or tetragonal crystals all singlet pairing states other than ``s wave'' would lead to \ensuremath{\Delta}${\ensuremath{\lambda}}_{\mathit{a}\mathit{b}}$(T)==${\ensuremath{\lambda}}_{\mathit{a}\mathit{ ...
Tópico(s): Magnetic and transport properties of perovskites and related materials
1991 - American Physical Society | Physical review. B, Condensed matter
Nigel J. Cockroft, John C. Wright,
Site-selective spectroscopy of rare-earth-doped materials has proven to be a powerful method for investigating solid-state defect chemistry at the atomic level. In this paper, the spectral transitions of single-crystal and polycrystalline samples of ${\mathrm{SrTiO}}_{3}$:${\mathrm{Eu}}^{3+}$ are sorted by site-selective laser spectroscopy into the major and minor sites that are found in this perovskite-structure material. The major site is shown to have crystal-field multiplicities, relative fluorescence ...
Tópico(s): Electronic and Structural Properties of Oxides
1992 - American Physical Society | Physical review. B, Condensed matter
Robert F. Klie, Haibin Su, Ye Zhu, J. W. Davenport, Juan Carlos Idrobo, Nigel D. Browning, Peter D. Nellist,
We have examined polycrystalline ${\mathrm{MgB}}_{2}$ by electron energy-loss spectroscopy (EELS) and density of states calculations. In particular, we have studied two different crystal orientations, [110] and [001], with respect to the incident electron beam direction, and found significant changes in the near-edge fine structure of the B K-edge. Density-functional theory suggests that the pre-peak of the B K-edge core loss is composed of a mixture of ${p}_{\mathrm{xy}}$- and ${p}_{z}$-hole states and we ...
Tópico(s): Hydrogen Storage and Materials
2003 - American Physical Society | Physical review. B, Condensed matter
Nigel R. Cooper, J. T. Chalker,
We examine the influence of Coulomb interactions on the integer quantum Hall effect in high-mobility, wide spacer-layer heterostructures. In these devices, the potential due to disorder is expected to be smooth on the scale of the spacer-layer thickness, which can be much larger than the magnetic length. Screening of this potential is accompanied by large fluctuations in electron density and has dramatic consequences. In particular, the screened potential can be pinned to the Fermi energy in regions ...
Tópico(s): Semiconductor materials and devices
1993 - American Physical Society | Physical review. B, Condensed matter
Nigel R. Cooper, Dmitri B. Chklovskii,
We study the theory of intrinsic photoluminescence of two-dimensional electron systems in the vicinity of the \ensuremath{\nu}=1 quantum Hall state. We focus predominantly on the recombination of a band of initial ``excitonic states'' that are the low-lying energy states of our model at \ensuremath{\nu}=1. It is shown that the recombination of excitonic states can account for recent observations of the polarization-resolved spectra of a high-mobility GaAs quantum well. The asymmetric broadening of the ...
Tópico(s): Advancements in Semiconductor Devices and Circuit Design
1997 - American Physical Society | Physical review. B, Condensed matter
In this paper we use multiple-scattering simulations in conjunction with experimental Z-contrast images and electron-energy-loss spectra to obtain a detailed analysis of the effect of the intrinsic structure of edge, screw, and mixed dislocations on the local density of unoccupied states in GaN. In particular, we show that the multiple scattering method is especially useful for examining dislocation cores where the bonding is significantly different at each atomic site in the structure. Furthermore, ...
Tópico(s): Ga2O3 and related materials
2002 - American Physical Society | Physical review. B, Condensed matter
Kevin Osborn, D. J. Van Harlingen, Vivek Aji, Nigel Goldenfeld, Seongshik Oh, J. N. Eckstein,
We report on a systematic investigation of the critical fluctuations in the complex conductivity of epitaxially-grown Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ films for ${T \lesssim T_c}$ using a two-coil inductive technique at zero applied field. We observe the static 3D-XY critical exponent in the superfluid density near $T_{c}$. Linear scaling analysis close to the critical temperature yields a dynamic critical exponent of $z = 2.0$ for small drive currents, but non-linear effects are seen to be important. ...
Tópico(s): Theoretical and Computational Physics
2003 - American Physical Society | Physical review. B, Condensed matter
Nigel D. Browning, Habib O. Moltaji, J. P. Buban,
Grain boundaries in oxide materials such as electroceramics, ferroelectrics, and high-${T}_{c}$ superconductors are known to dominate their overall bulk properties. The critical first step in a fundamental understanding of how they control the properties of the material is a determination of the atomic structure of the boundary. While this determination has traditionally been performed by transmission-electron microscopy, the images that are generated are only a two-dimensional projection of the ...
Tópico(s): Magnetic and transport properties of perovskites and related materials
1998 - American Physical Society | Physical review. B, Condensed matter
Nigel A. Marks, David R. McKenzie, Bernard Pailthorpe,
The relationship between the ion-beam energy and the stress in thin carbon films is studied using two-dimensional molecular-dynamics simulations. In agreement with experiment, a transition is seen from tensile to compressive stress with increasing ion energy. The compressive stress reaches a maximum near 30 eV, after which it slowly decreases. A significant result of the simulations is that the compressive stress does not arise from the implantation of ions beneath the surface layer as has been ...
Tópico(s): Metal and Thin Film Mechanics
1996 - American Physical Society | Physical review. B, Condensed matter
Gregory H. Bauer, David M. Ceperley, Nigel Goldenfeld,
Path-integral Monte Carlo simulations of liquid helium at negative pressure have been carried out for a temperature range from the critical temperature to below the superfluid transition. We have calculated the temperature dependence of the spinodal line as well as the pressure dependence of the isothermal sound velocity in the region of the spinodal. We discuss the slope of the superfluid transition line and the shape of the dispersion curve at negative pressures.
Tópico(s): High-pressure geophysics and materials
2000 - American Physical Society | Physical review. B, Condensed matter
Laurel J. Knott, Nigel J. Cockroft, John C. Wright,
The fluorescence spectra of erbium-doped strontium titanate were investigated as a function of sample preparation in order to probe the solid-state defect equilibrium. Erbium dopants double as donor dopants and as optical probes that reflect the variety of defect compensation mechanisms of strontium titanate. Erbium sites were correlated within the strontium titanate phases as a function of cation stoichiometry, dopant concentration, and annealing conditions. Unlike previously studied rare-earth ...
Tópico(s): Microwave Dielectric Ceramics Synthesis
1995 - American Physical Society | Physical review. B, Condensed matter
J. L. Osborne, A. J. Shields, M. Y. Simmons, Nigel R. Cooper, D. A. Ritchie, M. Pepper,
We report the observation of Coulomb interaction effects on the photoluminescence (PL) spectra of two-dimensional electron systems close to the $\ensuremath{\nu}=1$ quantum Hall state. Systematic measurements of the polarized PL spectrum as a function of the separation between the two-dimensional electron gas (2DEG) and the photoexcited valence-band hole allow us to identify the recombination mechanisms. These studies demonstrate the formation of bound states between the photoexcited valence-band hole ...
Tópico(s): Electronic and Structural Properties of Oxides
1998 - American Physical Society | Physical review. B, Condensed matter
Nigel R. Cooper, Bertrand I. Halperin, I. M. Ruzin,
We present a discussion of the linear thermoelectric response of an interacting electron gas in a quantizing magnetic field. Boundary currents can carry a significant fraction of the net current passing through the system. We derive general expressions for the bulk and boundary components of the number and energy currents. We show that the local current density may be described in terms of ``transport'' and ``internal magnetization'' contributions. The latter carry no net current and are not observable ...
Tópico(s): Advanced Thermoelectric Materials and Devices
1997 - American Physical Society | Physical review. B, Condensed matter