NQR investigation of high Tc superconductors under pressure

Guo qing Zheng, Etsuya Yanase, Kenji Ishida, Yoshio Kitaoka, Kunisuke Asayama, Yasuharu Kodama, Ritsu Tanaka, Sei Nakamichi, Shoichi Endo

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


The pressure dependence of the 63Cu nuclear quadrupole resonance (NQR) frequency, νQ, and Tc have been measured for La1.85Sr0.15CuO4 and YBa2Cu4O8 under high pressure up to 1.3GPa. νQ was found to decrease with increasing pressure in La1.85Sr0.15CuO4, while νQ in the CuO2 plane increases with pressure in YBa2Cu4O8. It is evidenced that charge transfer takes place under pressure. Based on the analysis that νQ arises mainly from the on-site holes, a schematic model relating Tc and the ratio of the in-plane hole concentration in the Cu3d and O2p orbitals, n(Cu)/n(O), is constructed. It is proposed that n(Cu)/n(O) is a primarily important factor governing Tc and that the enhancement of Tc under pressure is due to the change of the ratio approaching the most favorable value (∼1).

Original languageEnglish
Pages (from-to)51-55
Number of pages5
JournalSolid State Communications
Issue number1
Publication statusPublished - Jul 1991
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry


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