Spin and charge orders and their hole-doping dependence in single layered cobaltate La 2-xCa xCoO 4 (0.3 ≦ x ≦ 0.8)

Kazumasa Horigane, Haruhiro Hiraka, Toru Uchida, Kazuyoshi Yamada, Jun Akimitsu

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Neutron scattering experiments were performed on single crystals of layered cobalt-oxides La 2-xCa x-CoO 4 (LCCO) to characterize the charge and spin orders in a wide hole-doping range of 0.3 ≦ x ≦ 0.8. For a commensurate value of x = 0.5 in (H, 0, L) plane, two types of superlattice reflections concomitantly appear at low temperature; one corresponds to a checkerboard charge ordered pattern of Co 2+/ Co 3+ ions and the other is magnetic in origin. Further, the latter magnetic-superlattice peaks show two types of symmetry in the reflections, suggesting antiferromagnetic-stacking (AF-S) and ferromagnetic-stacking (F-S) patterns of spins along the c direction. From the hole-doping dependence, the in-plane correlation lengths of both charge and spin orders are found to give a maximum at x = 0.5. These features are the same with those of x = 0.5 in La i-xSr 1+xMnO 4 (LSMO), a typical checkerboard and spin ordered compound. However, in (H, H, L) plane, we found a magnetic scattering peak at Q = (0.25,0.25,0.5) position below T N. This magnetic peak can not be understood by considering the Co 2+ spin configuration, suggesting that this peak is originated from Co 3+ spin order. By analyzing these superlattice reflections, we found that they are originated from high-spin state of Co 3+ spin order.

Original languageEnglish
Article number114715
Journaljournal of the physical society of japan
Volume76
Issue number11
DOIs
Publication statusPublished - Nov 1 2007
Externally publishedYes

Keywords

  • Checkerboard charge order
  • Cobalt oxide
  • Neutron diffraction
  • Spin and charge order
  • Spin state of Co

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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