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Effect Of Orbital Symmetry Of The Tip On Scanning Tunneling Spectra Of Bi₂Sr₂Cacu₂O₈+Δ, Ilpo Suominen, Jouko Nieminen, R. S. Markiewicz, A. Bansil
Effect Of Orbital Symmetry Of The Tip On Scanning Tunneling Spectra Of Bi₂Sr₂Cacu₂O₈+Δ, Ilpo Suominen, Jouko Nieminen, R. S. Markiewicz, A. Bansil
Arun Bansil
We discuss how variations in the scanning tunneling microscope (STM) tip, whether unintentional or intentional, can lead to changes in topographic images and dI/dV spectra. We consider the possibility of utilizing functionalized tips in order to improve the sensitivity of STM experiments to local irregularities at the surface or hidden below the surface layers. The change in the tip symmetry can radically alter the contrast of the topographic image due to changes in tip-surface overlap. The dI/dV curves change their shape according to which sample bands the tip orbital tends to overlap. In addition, relative phases between competing tunneling channels …
Reconstructing The Bulk Fermi Surface And Superconducting Gap Properties From Neutron Scattering Experiments, Tanmoy Das, R. Markiewicz, A. Bansil
Reconstructing The Bulk Fermi Surface And Superconducting Gap Properties From Neutron Scattering Experiments, Tanmoy Das, R. Markiewicz, A. Bansil
Arun Bansil
We develop an analytical tool to extract bulk electronic properties of unconventional superconductors from inelastic neutron scattering spectra. We show that the upward and downward branches of the spin excitation spectra have distinct origins, with the upper branch representing a gapped spin-wave dispersion and the lower branch associated with Bogoliubov quasiparticle scattering on the Fermi surface. Combined, they produce an "hourglass" dispersion with 45 degrees rotation of the spectrum, as found experimentally. The downward dispersion can be inverted to reveal the Fermi momentum dispersion of the single-particle spectrum as well as the corresponding superconducting (SC) gap function, analogously to the …
Competing Order Scenario Of Two-Gap Behavior In Hole-Doped Cuprates, Tanmoy Das, R. Markiewicz, A. Bansil
Competing Order Scenario Of Two-Gap Behavior In Hole-Doped Cuprates, Tanmoy Das, R. Markiewicz, A. Bansil
Arun Bansil
Angle-dependent studies of the gap function provide evidence for the coexistence of two distinct gaps in hole doped cuprates, where the gap near the nodal direction scales with the superconducting transition temperature Tc, while that in the antinodal direction scales with the pseudogap temperature. We present model calculations which show that most of the characteristic features observed in the recent angle-resolved photoemission spectroscopy (ARPES) as well as scanning tunneling microscopy (STM) two-gap studies are consistent with a scenario in which the pseudogap has a non-superconducting origin in a competing phase. Our analysis indicates that, near optimal doping, superconductivity can quench …