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Article
Open AccessPairing in a dry Fermi sea
In the traditional Bardeen–Cooper–Schrieffer theory of superconductivity, the amplitude for the propagation of a pair of electrons with momentum k and −k has a log singularity as the temperature decreases. This s...
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Article
Open AccessEmergence of coherence in the charge-density wave state of 2H-NbSe2
A charge-density wave (CDW) state has a broken symmetry described by a complex order parameter with an amplitude and a phase. The conventional view, based on clean, weak-coupling systems, is that a finite ampl...
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Article
Effect of the pseudogap on the transition temperature in the cuprates and implications for its origin
An argument by contradiction shows that the pseudogap state in the high-temperature superconducting cuprates is due to the superconducting pairing rather than being an independent or even competing state.
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Article
Observation of a d-wave nodal liquid in highly underdoped Bi2Sr2CaCu2O8+δ
High-temperature superconductivity in the cuprates arises when charge carriers are added to an insulator. Between these states lies the so-called nodal liquid at low temperature. Photoemission spectroscopy sug...
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Chapter
Photoemission in the High-T c Superconductors
Photoemission: Photoemission results in high transtion temperature superconductors are discussed. Thus, basic properties like the spectral density, the Fermi surface topology, the pseudogap and the superconduc...
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Article
Evolution of the pseudogap from Fermi arcs to the nodal liquid
The response of a material to external stimuli depends on its low-energy excitations. In conventional metals, these excitations are electrons on the Fermi surface—a contour in momentum (k) space that encloses all...
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Chapter
Photoemission in the High-T c Superconductors
Angle resolved photoemission spectroscopy (ARPES) has played a major role in the elucidation of the electronic excitations in the high temperature cuprate superconductors. Several reasons have contributed to t...
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Article
The origin of multiple superconducting gaps in MgB2
Magnesium diboride, MgB2, has the highest transition temperature (Tc = 39 K) of the known metallic superconductors1. Whether the anomalously high Tc can be described within the conventional BCS (Bardeen–Cooper–Sc...
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Article
Spontaneous breaking of time-reversal symmetry in the pseudogap state of a high-Tc superconductor
A change in ‘symmetry’ is often observed when matter undergoes a phase transition—the symmetry is said to be spontaneously broken. The transition made by underdoped high-transition-temperature (high-Tc) supercond...
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Chapter
Summary of Arpes Results on the Pseudogap in Bi2Sr2CaCu2O8+δ
We summarize our angle-resolved photoemission (ARPES) results on the pseu- dogap observed in the high temperature superconductor Bi2 Sr2CaCu2 O8+δ such as temperature, momentum and do** dependencies.
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Article
BSCCO Superconductors: Hole-Like Fermi Surface and Do** Dependence of the Gap Function
We use the gradient of the energy-integrated angle resolved photoemission (ARPES) intensity in order to define precisely the Fermi surface (FS) in BSCCO superconductors. We show that, independent of the photon.....
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Article
Destruction of the Fermi surface in underdoped high-Tc superconductors
The Fermi surface—the set of points in momentum space describing gapless electronic excitations—is a central concept in the theory of metals. In this context, the normal ‘metallic’ state of the optimally doped...
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Article
Spectroscopic evidence for a pseudogap in the normal state of underdoped high-Tc superconductors
IT is well known that BCS mean-field theory is remarkably successful in describing conventional superconductors. A central concept of BCS theory is the energy gap in the electronic excitation spectrum below t...
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Article
Photoemission from the highT c superconductors
The electronic structures of Y Ba2Cu3Ox and YBa2Cu4O8 were studied by angleresolved photoemission with an energy resolution of better than 10 meV. A detailed study in the 1st and 2nd Brillouin zone of untwinned s...
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Article
Reconstruction of the 3-D Atomic Structure of CoSi2(111) by Photoelectron Holography
We report the use of photoelectron holography for the study of the atomic geometry of the (111) surface of single crystal CoSi2. We employ as a reference wave the Co 3p core electron emitted with a kinetic energy...
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Article
First-Principles Angle-Resolved Photoemission Intensity Calculations in Y Ba2Cu3O7
We discuss the application of the multiple scattering theory to obtain first-principles predictions of angle-resolved photoemission intensities (ARPES) in the high-Tc superconductors. In this connection, we have ...
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Chapter and Conference Paper
Normal State Electronic Structure and the Superconducting Energy Gap in HTSC’s as Determined from Photoemission Spectroscopy
Photoemission spectroscopy is utilized to determine the electronic structure of high-Tc materials. The observation of dispersive bands at EF suggests a Fermi surface similar to that obtained from a band calculati...
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Article
Photoemission Spectroscopy of Single Crystal HTSC Materials: A Fermi Liquid Electronic Structure
Photoemission spectra from HTSC materials ( primarily 123 -type ), cleaved and measured at 20K, reveal a rich DOS structure which compares favorably with a calculated band structure, except for a residual 0.5 ...
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Chapter and Conference Paper
Conformal Invariance, Multiple Scattering and the Au(110) (1×2) to (1×1) Phase Transition
Conformal invariance predicts the scattering lineshape and full dependence on scattering parameters for LEED (Low-Energy Electron Diffraction) intensities from finite regions at second-order phase transitions ...
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Chapter and Conference Paper
A SEXAFS Study of Iodine on Ni{100}: The Surface Iodide Phase
This adsorption system shows several surface phases [1, 2] at room temperature. A c(2x2) chemisorbed phase is formed by exposure of Ni{100} to iodine vapour at room temperature, while a “surface iodide” is for...
