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in subjects: "Charge Density"

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Solid electrolytes and impact-resistant ceramics. [Progress report]

In this proposal, we describe a program to exploit recent achievements in two distinct areas of materials science, both of them dependent on the independent motion of singly charged ions through an immobile matrix. The first is the area of non-crystalline solid electrolytes in which this laboratory has gained prominence over the past decade. The second is an area proposed for study in our previous proposal and now verified as a principle worthy of considerable further investigation: it involves… more

Date: August 1991

Creator: Angell, C. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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X-ray scattering studies of non-equilibrium ordering processes. Progress report, November 1, 1989--October 31, 1992

This report summarizes the major results obtained under US DOE Grant Number FG05-90ER45280 from the dates November 1, 1989 through October 31, 1992 inclusive. The principal work includes x-ray scattering studies of phase transition kinetics in binary alloy order-disorder transitions, block co-polymer crystallization, and charge density wave solids under applied electric fields, and studies of magnetic excitations in low dimensional quantum systems.

Date: June 1, 1992

Creator: Nagler, S. E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Calculations of nonspherically averaged charge densities for subtitutionally disordered alloys

Based on screening transformations of muffin-tin orbitals introduced by Andersen et al. [Phys. Rev. Lett. 53, 2571 (1984)], we have developed a formalism for calculating the non-spherically averaged charge densities of substitutionally disordered alloys using the Korringa-Kohn-Rostoker coherent potential approximation (KKR CPA) method in the atomic-sphere approximation (ASA). We have validated our method by calculating charge densities for ordered structures, where we find that our approach yie… more

Date: February 1, 1994

Creator: Singh, P. P. & Gonis, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Origin of charge density at LaAlO3-on-SrTiO3 heterointerfacespossibility of intrinsic doping

As discovered by Ohtomo et al., a large sheet charge density with high mobility exists at the interface between SrTiO{sub 3} and LaAlO{sub 3}. Based on transport, spectroscopic and oxygen-annealing experiments, we conclude that extrinsic defects in the form of oxygen vacancies introduced by the pulsed laser deposition process used by all researchers to date to make these samples is the source of the large carrier densities. Annealing experiments show a limiting carrier density. We also present … more

Date: April 29, 2010

Creator: Siemons, W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Unanticipated results in the uranium niobium alloy system

The uranium niobium binary alloy system exhibits a rich collection of phenomena for study. The composition range from 0 wt.% Nb to 10 wt.% Nb exhibits multiple crystallographic phases with interesting properties such as superconductivity, charge density waves and shape memory effects. We have measured the resistivity and heat capacity as a function of temperature from 2 to 325K in the above composition range in an effort to map out the phase boundaries of interest. Surprisingly the temperature … more

Date: January 1, 2002

Creator: Cooley, Jason C.; Hults, William L.; Dauelsberg, Lawrence B.; Thoma, Dan J.; Peterson, Eric J.; Teter, David F. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Chemical pressure and hidden one-dimensional behavior in rare earth tri-telluride

We report on the first optical measurements of the rare-earth tri-telluride charge-density-wave systems. Our data, collected over an extremely broad spectral range, allow us to observe both the Drude component and the single-particle peak, ascribed to the contributions due to the free charge carriers and to the charge-density-wave gap excitation, respectively. The data analysis displays a diminishing impact of the charge-density-wave condensate on the electronic properties with decreasing latti… more

Date: December 14, 2009

Creator: Sacchetti, A.; Degiorgi, L.; Giamarchi, T.; Ru, N. & Fisher, I. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Monte Carlo Mean Field Treatment of Microbunching Instability in the FERMI@Elettra First Bunch Compressor

Bunch compressors, designed to increase the peak current, can lead to a microbunching instability with detrimental effects on the beam quality. This is a major concern for free electron lasers (FELs) where very bright electron beams are required, i.e. beams with low emittance and energy spread. In this paper, we apply our self-consistent, parallel solver to study the microbunching instability in the first bunch compressor system of FERMI{at}Elettra. Our basic model is a 2D Vlasov-Maxwell system… more

Date: May 7, 2009

Creator: Bassi, G.; Ellison, J. A.; Heinemann, K. & Warnock, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fermi Surface Evolution Across Multiple Charge Density Wave Transitions in ErTe3

The Fermi surface (FS) of ErTe{sub 3} is investigated using angle-resolved photoemission spectroscopy (ARPES). Low temperature measurements reveal two incommensurate charge density wave (CDW) gaps created by perpendicular FS nesting vectors. A large {Delta}{sub 1} = 175 meV gap arising from a CDW with c* - q{sub CDW1} {approx} 0.70(0)c* is in good agreement with the expected value. A second, smaller {Delta}{sub 2} = 50 meV gap is due to a second CDW with a* - q{sub CDW2} {approx} 0.68(5)a*. The… more

Date: February 15, 2010

Creator: Moore, R. G.; /SLAC, SSRL /Stanford U., Geballe Lab.; Brouet, V.; /Orsay, LPS; He, R.; /SLAC, SSRL /Stanford U., Geballe Lab. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Pressure Dependence of the Charge-Density-Wave Gap in Rare-Earth Tri-Tellurides

We investigate the pressure dependence of the optical properties of CeTe{sub 3}, which exhibits an incommensurate charge-density-wave (CDW) state already at 300 K. Our data are collected in the mid-infrared spectral range at room temperature and at pressures between 0 and 9 GPa. The energy for the single particle excitation across the CDW gap decreases upon increasing the applied pressure, similarly to the chemical pressure by rare-earth substitution. The broadening of the bands upon lattice co… more

Date: December 14, 2009

Creator: Sacchetti, A.; /Zurich, ETH; Arcangeletti, E.; Perucchi, A.; Baldassarre, L.; Postorino, P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Single-particle and collective mode couplings associated with 1- and 2-directional electronic ordering in metallic RTe3 (R = Ho, Dy, Tb)

The coupling of phonons with collective modes and single-particle gap excitations associated with one (1d) and two-directional (2d) electronically-driven charge-density wave (CDW) ordering in metallic RTe{sub 3} is investigated as a function of rare-earth ion chemical pressure (R = Tb, Dy, Ho) using femtosecond pump-probe spectroscopy. From the T-dependence of the CDW gap {Delta}{sub CDW} and the amplitude mode (AM) we find that while the transition to a 1d-CDW ordered state at Tc1 initially pr… more

Date: February 15, 2010

Creator: Yusupov, R. V.; Mertelj, T.; Chu, J.-H.; Fisher, I. R. & Mihailovic, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Angle-resolved photoemission study of the evolution of band structure and charge density wave properties in RTe3 (R= Y, La, Ce, Sm, Gd, Tb and Dy)

We present a detailed ARPES investigation of the RTe{sub 3} family, which sets this system as an ideal 'textbook' example for the formation of a nesting driven Charge Density Wave (CDW). This family indeed exhibits the full range of phenomena that can be associated to CDW instabilities, from the opening of large gaps on the best nested parts of Fermi Surface (FS) (up to 0.4eV), to the existence of residual metallic pockets. ARPES is the best suited technique to characterize these features, than… more

Date: February 15, 2010

Creator: Brouet, V.; Yang, W. L.; Zhou, X. J.; Hussain, Z.; Moore, R. G.; He, R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Analytical studies of coherent electron cooling

Under certain assumptions and simplifications, we studied a few physics processes of Coherent Electron Cooling using analytical approach. In the modulation process, the effect due to merging the ion beam with the electron beam is studied under single kick approximation. In the free electron laser (FEL) amplifier, we studied the amplification of the electron density modulation using 1D analytical approach. Both the electron charge density and the phase space density are derived in the frequency … more

Date: May 4, 2009

Creator: Wang, G.; Blaskiewicz, M. & Litvinenko, V. N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Pressure induced Superconductivity in the Charge Density Wave Compound Tritelluride

A series of high-pressure electrical resistivity measurements on single crystals of TbTe{sub 3} reveal a complex phase diagram involving the interplay of superconducting, antiferromagnetic and charge density wave order. The onset of superconductivity reaches a maximum of almost 4 K (onset) near {approx} 12.4 GPa.

Date: February 15, 2010

Creator: Hamlin, J.J.; Zocco, D. A.; Sayles, T. A.; Maple, M. B.; Chu, J.-H.; Fisher, I.R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Multiple charge density wave transitions in Gd2Te5

Diffraction measurements performed via transmission electron microscopy and high resolution X-ray scattering reveal two distinct charge density wave transitions in Gd{sub 2}Te{sub 5} at T{sub c1} = 410(3) and T{sub c2} = 532(3) K, associated with the on-axis incommensurate lattice modulation and off-axis commensurate lattice modulation respectively. Analysis of the temperature dependence of the order parameters indicates a non-vanishing coupling between these two distinct CDW states.

Date: February 15, 2010

Creator: Shin, K. Y.; Ru, N.; Condron, C. L.; Wu, Y. Q.; Kramer, M. J.; Toney, M. F. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Ion distributions at charged aqueous surfaces: Synchrotron X-ray scattering studies

Surface sensitive synchrotron X-ray scattering studies were performed to obtain the distribution of monovalent ions next to a highly charged interface at room temperature. To control surface charge density, lipids, dihexadecyl hydrogen-phosphate (DHDP) and dimysteroyl phosphatidic acid (DMPA), were spread as monolayer materials at the air/water interface, containing CsI at various concentrations. Five decades in bulk concentrations (CsI) are investigated, demonstrating that the interfacial dist… more

Date: August 15, 2009

Creator: Bu, Wei

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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Optical properties of the Ce and La ditelluride charge density wave compounds

The La and Ce di-tellurides LaTe{sub 2} and CeTe{sub 2} are deep in the charge-density-wave (CDW) ground state even at 300 K. We have collected their electrodynamic response over a broad spectral range from the far infrared up to the ultraviolet. We establish the energy scale of the single particle excitation across the CDW gap. Moreover, we find that the CDW collective state gaps a very large portion of the Fermi surface. Similarly to the related rare earth tri-tellurides, we envisage that int… more

Date: February 15, 2010

Creator: Lavagnini, M.; Sacchetti, A.; Degiorgi, L.; Shin, K. Y. & Fisher, I. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Magnetic properties of the charge density wave compounds RTe3, R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er & Tm

The antiferromagnetic transition is investigated in the rare-earth (R) tritelluride RTe{sub 3} family of charge density wave (CDW) compounds via specific heat, magnetization and resistivity measurements. Observation of the opening of a superzone gap in the resistivity of DyTe{sub 3} indicates that additional nesting of the reconstructed Fermi surface in the CDW state plays an important role in determining the magnetic structure.

Date: December 14, 2009

Creator: Ru, N.; Chu, J.-H.; Fisher, I.R. & /Stanford U., Geballe Lab.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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De Haas-van Alphen oscillations in the charge-density wave compound lanthanum tritelluride (LaTe3)

De Haas-van Alphen oscillations were measured in lanthanum tritelluride (LaTe{sub 3}) to probe the partially gapped Fermi surface resulting from charge density wave (CDW) formation. Three distinct frequencies were observed, one of which can be correlated with a FS sheet that is unaltered by CDW formation. The other two frequencies arise from FS sheets that have been reconstructed in the CDW state.

Date: December 14, 2009

Creator: Ru, N.; Borzi, R. A.; Rost, A.; Mackenzie, A. P.; Laverock, J.; Dugdale, S. B. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Coexistence of ferromagnetism and superconductivity in cerium, tellurium (1.82).

CeTe1 .82 crystallizes in layered tetragonal Cu2Sb-type structure. At ambient pressure, the presence of the charge density wave (CDW) gap accompanying with a lattice distortion in the Te sheet is verified by electron-tunneling spectroscopy measurement. We measured the electrical resistivity on a CeTe1 .82 single crystal as a function of temperature and magnetic field (i // ab-plain, H// c-axis) performed under hydrostatic pressure up to 9 kbar using the 20 T superconduting magnet at the Pulse F… more

Date: January 1, 2003

Creator: Asmadi, A. M.; Jung, M. (Myung-Hwa); Kim, H. C. (Hyoung-Chan); Kamarad, J.; Lacerda, A. H. (Alex H.); Takabatake, T. (Toshiro) et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Polarized gun and ERL R and D for eRHIC

At Jefferson Laboratory charge density and charge lifetime during electron beam delivery are over 2 x 10{sup 5} C/cm{sup 2} and 200 C, respectively. A 200 C charge lifetime at 2 mA corresponds to 10{sup 5} seconds. In a more recent result, charge lifetimes of about an order of magnitude larger were achieved by a load-lock gun with a larger cathode area.

Date: May 27, 2009

Creator: Ben-Zvi, Ilan

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Simple Limits on Achieving A Quasi-Linear Magnetic Compression for an FEL Driver

Free electron lasers (FEL) need a very bright electron beam in three dimensions and a high peak charge density. In order to compress an initially longer electron bunch generated from the photoinjector, magnetic bunch compression systems are widely employed. In this paper, first harmonic RF linearization and its associated requirements are reviewed. Meanwhile it is also briefly discussed what is the relation between a proper initial bunch length and main RF frequency, when a harmonic RF lineariz… more

Date: February 16, 2012

Creator: Sun, Yipeng

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Realizing vector meson dominance with transverse charge densities

The transverse charge density in a fast-moving nucleon is represented as a dispersion integral of the imaginary part of the Dirac form factor in the timelike region (spectral function). At a given transverse distance b the integration effectively extends over energies in a range {radical}t {approx}< 1/b, with exponential suppression of larger values. The transverse charge density at peripheral distances thus acts as a low-pass filter for the spectral function and allows one to select energy … more

Date: October 1, 2011

Creator: Gerald Miller, Mark Strikman, Christian Weiss

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electron Beam Charge Diagnostics for Laser Plasma Accelerators

A comprehensive study of charge diagnostics is conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). First, a scintillating screen (Lanex) was extensively studied using subnanosecond electron beams from the Advanced Light Source booster synchrotron, at the Lawrence Berkeley National Laboratory. The Lanex was cross calibrated with an integrating current transformer (ICT) for up to the electron energy of 1.5 GeV, and the linear response of t… more

Date: June 27, 2011

Creator: Nakamura, Kei; Gonsalves, Anthony; Lin, Chen; Smith, Alan; Rodgers, David; Donahue, Rich et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Thermodynamic and Transport Properties of YTe3, LaTe3 and CeTe3

Measurements of heat capacity, susceptibility, and electrical resistivity are presented for single crystals of the charge density wave compounds YTe{sub 3}, LaTe{sub 3}, and CeTe{sub 3}. The materials are metallic to low temperatures, but have a small density of states due to the charge density wave gapping large portions of the Fermi surface. CeTe{sub 3} is found to be a weak Kondo lattice, with an antiferromagnetic ground state and T{sub N} = 2.8 K. The electrical resistivity of all three com… more

Date: August 19, 2011

Creator: Ru, N.

Item Type: Article

Partner: UNT Libraries Government Documents Department