"Probing the Energy Gap of High Temperature Superconductors with Tunneling Spectroscopy: Evidence for Exotic Pairing"
Prof. John Zasadzinski

Oct 21, 1999


講演題目: Probing the Energy Gap of High Temperature Superconductors with Tunneling Spectroscopy: Evidence for Exotic Pairing
講 師 : Prof. John Zasadzinski
     (Illinois Institute of Technology and Argonne National Laboratory)
日 時 : 平成11年10月21日 (木) 16:30-17:00
場 所 : 北海道大学理学部2号館大学院講義室(2-2-11)

要 旨 :
TTunneling spectroscopy is presented for a variety of high temperature superconducting cuprates. The data for electron doped compounds such as Nd-Ce-Cu-O which have a relatively low Tc = 22K are consistent with an s-wave energy gap and ordinary phonon mediated pairing. However, the tunneling data for hole-doped cuprates such as Bi-Sr-Ca-Cu-O (Bi2212) with an optimal Tc = 95 K are more consistent with a d-wave energy gap. The doping dependence of the energy gap parameter in Bi2212 is anomalous, increasing to very large values in the underdoped regime even as Tc decreases. This gap parameter follows the trend of the antiferromagnetic exchange energy, J, which indicates that the pairing is of magnetic origin.  The high bias tunneling spectra reveal a dip feature that is often quite pronounced and may be related to the resonance peak in the magnetic excitations probed by neutron scattering. Also, the high bias features include a secondary peak which might be an indication of a competing pseudogap of magnetic origin.

小田研 (北海道大学大学院理学研究科)
(moda@sci.hokudai.ac.jp)


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