NMR study in novel superconductors: Heavy-fermion system and high-Tc cuprate

Y. Kitaoka, K. Ishida, Guo-Qing Zheng, H. Tou, K. Magishi, S. Matsumoto, K. Yamazoe, H. Yamanaka, K. Asayama

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Abstract

From the NMR and NQR studies, we show the unconventional superconducting properties in the antiferromagnetic (AF) heavy-fermion (HF), UPd2Al3 and high-Tc cuprate systems. In UPd2Al3 with TN = 14.5 K and Tc = 2 K, the superconductivity is shown to be of d-wave pairing type with lines of vanishing gap on the Fermi surface. The potential scattering associated with some defects at the Al site is the cause for the Tc suppression and the appearance of the density of states (DOS) at the Fermi level. This unusual impurity effect is consistent with a d-wave scenario, because the potential scattering leads to a gap opening for an anisotropic s-wave scenario. In high-Tc cuprate which are argued to be either a d-wave or an anisotropic s-wave, the potential scatterer like Zn in the plane induces the gapless superconductivity as well, which can not be interpreted in terms of an anisotropic s-wave scenario if the order parameter does not change sign largely. It is shown from the NMR experiment at the Al site for Al-doped La1.85Sr0.15CuO4 that local moments at near neighbor Cu sites induced around Al impurity do not play a role to suppress the Tc and to induce the DOS at all. The NMR studies in novel superconductors have provided important clues to identify their symmetry of order parameter to be d-wave.

Original languageEnglish
Pages (from-to)1931-1935
Number of pages5
JournalJournal of Physics and Chemistry of Solids
Volume56
Issue number12
Publication statusPublished - Dec 1995
Externally publishedYes

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Keywords

  • d-wave superconductivity
  • heavy fermion system
  • high-T cuprate
  • NMR
  • NQR

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Materials Science(all)
  • Chemistry(all)
  • Electronic, Optical and Magnetic Materials

Cite this

Kitaoka, Y., Ishida, K., Zheng, G-Q., Tou, H., Magishi, K., Matsumoto, S., Yamazoe, K., Yamanaka, H., & Asayama, K. (1995). NMR study in novel superconductors: Heavy-fermion system and high-Tc cuprate. Journal of Physics and Chemistry of Solids, 56(12), 1931-1935.