5 research outputs found
Tunneling into Current-Carrying Surface States of High T Superconductors
Theoretical results for the ab-plane tunneling conductance in the d-wave
model for high Tc superconductors are presented. The d-wave model predicts
surface bound states below the maximum gap. A sub-dominant order parameter,
stabilized by the surface, leads to a splitting of the zero-bias conductance
peak (ZBCP) in zero external field and to spontaneous surface currents. In a
magnetic field screening currents shift the quasiparticle bound state spectrum
and lead to a voltage splitting of the ZBCP that is linear in H at low fields,
and saturates at a pairbreaking critical field of order 3 Tesla. Comparisons
with recent experimental results on Cu/YBCO junctions are presented.Comment: 4 pages in a RevTex (3.0) file plus 3 Figures in PostScript. To
appear in Phys. Rev. Let
Strongly correlated s-wave pairing in the n-type infinite-layer cuprate
Quasiparticle tunneling spectra of the electron-doped (n-type) infinite-layer
cuprate Sr_{0.9}La_{0.1}CuO_2 reveal characteristics that counter a number of
common phenomena in the hole-doped (p-type) cuprates. The optimally doped
Sr_{0.9}La_{0.1}CuO_2 with T_c = 43 K exhibits a momentum-independent
superconducting gap \Delta = 13.0 +- 1.0 meV that substantially exceeds the BCS
value, and the spectral characteristics indicate insignificant quasiparticle
damping by spin fluctuations and the absence of pseudogap. The response to
quantum impurities in the Cu-sites also differs fundamentally from that of the
p-type cuprates with d_{x^2-y^2}-wave pairing symmetry.Comment: 4 pages, 3 figures. Published in Physical Review Letter.
Corresponding author: Nai-Chang Yeh (e-mail: [email protected]
Shot noise in normal metal-d-wave superconducting junctions
We present theoretical calculations and predictions for the shot noise in
voltage biased junctions of superconductors and normal metal
counter-electrodes. In the clean limit for the d-wave superconductor the shot
noise vanishes at zero voltage because of resonant Andreev reflection by
zero-energy surface bound states. We examine the sensitivity of this resonance
to impurity scattering. We report theoretical results for the magnetic field
dependence of the shot noise, as well the fingerprints of subdominant - and
pairing channels.Comment: 15 pages, 8 figures and 3 tables embedde