Wednesday, March 16, 2011, 1:00 pm — Bldg. 480 Conference Room
We explore the superconducting state of hole-doped cuprates by electronic Raman scattering
as a function of both temperature and doping level.
We observe a loss of coherent quasi-particles in the anti-nodal region (where the
superconducting gap amplitude is maximum). We show that coherent Bogoliubov quasiparticles
develop preferentially around the nodal region (where the gap amplitude vanishes).
Most of the super-current is then carried out by electronic states around the nodes. This
contrasts to conventional superconductors where superconductivity develops uniformly along
the normal-state Fermi surface.
We can then define the fraction of coherent Fermi surface, fc around the nodes for which
quasi-particles are well defined and superconductivity sets in. We find that fc is doping
dependent and we establish that Tc ∝ fc Δmax where Δmax is the maximum amplitude of the dwave
superconducting gap. This new relation differs from the standard BCS theory and gives
us some clues for increasing Tc in the cuprates.
S. Blanc, Y. Gallais, M. Cazayous, M. A. Méasson, A. Sacuto, A. Georges, J. S. Wen, Z. J.
Xu, G. D. Gu, and D. Colson, Phys. Rev. B 82, 144516 (2010).
S. Blanc, Y. Gallais, A. Sacuto, M. Cazayous, M. A. Méasson, G. D. Gu, J. S. Wen, and Z. J.
Xu, Phys. Rev. B 80, 140502 (2009).
Hosted by: Genda Gu
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