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Revealing Charge Density Wave Formation in the LaTe2 System byAngle Resolved Photoemission Spectroscopy

Description: We present the first direct study of charge density wave(CDW) formation in quasi-2D single layer LaTe2 using high-resolutionangle resolved photoemission spectroscopy (ARPES) and low energy electrondiffraction (LEED). CDW formation is driven by Fermi surface (FS)nesting, however characterized by a surprisingly smaller gap (~;50 meV)than seen in the double layer RTe3 compounds, extending over the entireFS. This establishes LaTe2 as the first reported semiconducting 2D CDWsystem where the CDW phas… more
Date: November 15, 2006
Creator: Garcia, D. R.; Gweon, G.-H.; Zhou, S. Y.; Graf, J.; Jozwiak, C. M.; Jung, M. H. et al.
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Partner: UNT Libraries Government Documents Department
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Angle-resolved photoemission spectroscopy (ARPES) studies of cuprate superconductors

Description: This dissertation is comprised of three different angle-resolved photoemission spectroscopy (ARPES) studies on cuprate superconductors. The first study compares the band structure from two different single layer cuprates Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}} (Tl2201) T{sub c,max} {approx} 95 K and (Bi{sub 1.35}Pb{sub 0.85})(Sr{sub 1.47}La{sub 0.38})CuO{sub 6+{delta}} (Bi2201) T{sub c,max} {approx} 35 K. The aim of the study was to provide some insight into the reasons why single layer cuprate's … more
Date: December 15, 2010
Creator: Palczewski, Ari Deibert
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Partner: UNT Libraries Government Documents Department
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Fermi Surface Evolution Across Multiple Charge Density Wave Transitions in ErTe3

Description: 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.
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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)

Description: 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.
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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)

Description: 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.
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Partner: UNT Libraries Government Documents Department
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Pressure induced Superconductivity in the Charge Density Wave Compound Tritelluride

Description: 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.
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Partner: UNT Libraries Government Documents Department
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Multiple charge density wave transitions in Gd2Te5

Description: 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.
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Partner: UNT Libraries Government Documents Department
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Ion distributions at charged aqueous surfaces: Synchrotron X-ray scattering studies

Description: 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: Refine your search to only 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

Description: 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.
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Partner: UNT Libraries Government Documents Department
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STM Studies of TbTe3: Evidence for a Fully Incommensurate Charge Density Wave

Description: We observe unidirectional charge density wave ordering on the cleaved surface of TbTe{sub 3} with a Scanning Tunneling Microscope at {approx}6 K. The modulation wave-vector q{sub CDW} as determined by Fourier analysis is 0.71 {+-} 0.02 x2{pi}/c. Where c is one edge of the in-plane 3D unit cell. Images at different tip-sample voltages show the unit cell doubling effects of dimerization and the layer below. Our results agree with bulk X-ray measurements, with the addition of (1/3) x2{pi}/a orderi… more
Date: February 15, 2010
Creator: Fang, A.; Ru, N.; Fisher, I.R.; /Stanford U., Appl. Phys. Dept.; Kapitulnik, A. & /Stanford U., Appl. Phys. Dept. /Stanford U., Phys. Dept.
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Partner: UNT Libraries Government Documents Department
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Resonant Enhancement of Charge Density Wave Diffraction in the Rare-Earth Tri-Tellurides

Description: We performed resonant soft X-ray diffraction on known charge density wave (CDW) compounds, rare earth tri-tellurides. Near the M{sub 5} (3d - 4f) absorption edge of rare earth ions, an intense diffraction peak is detected at a wavevector identical to that of CDW state hosted on Te{sub 2} planes, indicating a CDW-induced modulation on the rare earth ions. Surprisingly, the temperature dependence of the diffraction peak intensity demonstrates an exponential increase at low temperatures, vastly di… more
Date: May 15, 2012
Creator: Lee, W. S.; Sorini, A. P.; Yi, M.; Chuang, Y. D.; Moritz, B.; Yang, W. L. et al.
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Partner: UNT Libraries Government Documents Department
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