Spin gap and hole pairing in the spin-ladder cuprate Sr14-cursive Greek chiAcursive Greek chiCu24O41 (A=Ca and La) studied by the thermal conductivity

Kazutaka Kudo, Satoru Ishikawa, Takashi Noji, Tadashi Adachi, Yoji Koike, Katsuhiko Maki, Shigenori Tsuji, Ken Ichi Kumagai

Research output: Contribution to journalArticlepeer-review

68 Citations (Scopus)

Abstract

We have systematically measured the thermal conductivity κ of Sr14-cursive Greek chiAcursive Greek chiCu24O41 (A=Ca, La: 0 ≤ cursive Greek chi(Ca) ≤ 9: 0 ≤ cursive Greek chi(La) ≤ 5) single crystals, in order to investigate the spin gap and hole pairing. The observed κ has been analyzed to be composed of κph, κspin and κhole due to phonons, spins and holes, respectively. The contribution of κspin is observed only along the c-axis except for cursive Greek chi(Ca) ≥ 6. The spin gap in the ladder estimated from κspin is ∼400K and independent of cursive Greek chi. This is regarded as corresponding to the spin excitation from spin-singlet to spin-triplet, as those estimated from the neutron scattering and Raman scattering measurements. The contribution of κhole is observed at high temperatures for larger cursive Greek chi(Ca) values. The activation energy of holes in the ladder estimated from κhole decreases with increasing cursive Greek chi(Ca). This is regarded as corresponding to the dissociation of hole pairs, as that estimated from the electrical resistivity measurements. These results are consistent with the recent suggestion that most of holes are paired and localized in the ladder at low temperatures.

Original languageEnglish
Pages (from-to)437-444
Number of pages8
Journaljournal of the physical society of japan
Volume70
Issue number2
DOIs
Publication statusPublished - Feb 1 2001
Externally publishedYes

Keywords

  • Spin gap
  • Spin ladder system
  • Sr(Ca,La)cursive greek chiCuo single crystal
  • Thermal conductivity

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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