35 research outputs found
Evolution of a bosonic mode across the superconducting dome in the high-Tc cuprate Pr(2-x)Ce(x)CuO(4-{\delta})
We report a detailed spectroscopic study of the electron doped cuprate
superconductor Pr(2-x)Ce(x)CuO(4-{\delta}) using point contact junctions for
x=0.125(underdoped), x=0.15(optimally doped) and x=0.17(overdoped). From our
conductance measurements we are able to identify bosonic resonances for each
doping. These excitations disappear above the critical temperature, and above
the critical magnetic field. We find that the energy of the bosonic excitations
decreases with doping, which excludes lattice vibrations as the paring glue. We
conclude that the bosonic mediator for these cuprates is more likely to be spin
excitations.Comment: 4 page
Coexistence of a triplet nodal order-parameter and a singlet order-parameter at the interfaces of ferromagnet-superconductor Co/CoO/In junctions
We present differential conductance measurements of Cobalt / Cobalt-Oxide /
Indium planar junctions, 500nm x 500nm in size. The junctions span a wide range
of barriers, from very low to a tunnel barrier. The characteristic conductance
of all the junctions show a V-shape structure at low bias instead of the
U-shape characteristic of a s-wave order parameter. The bias of the conductance
peaks is, for all junctions, larger than the gap of indium. Both properties
exclude pure s-wave pairing. The data is well fitted by a model that assumes
the coexistence of s-wave singlet and equal spin p-wave triplet fluids. We find
that the values of the s-wave and p-wave gaps follow the BCS temperature
dependance and that the amplitude of the s-wave fluid increases with the
barrier strength.Comment: 5 pages, Accepted to Phys. Rev.