Coexistence of S = 1/2 antiferromagnetic chains and dimers on hole-doped CuO2 chains in Ca1-xCuO2

Zenji Hiroi, Makoto Okumura, Takahiro Yamada, Mikio Takano

研究成果: Article査読

19 被引用数 (Scopus)

抄録

Quasi-one-dimensional cupric oxide Ca1-xCuO2+δ, comprising 25-50% hole-doped edge-sharing CuO2 chains, is studied by uniform magnetic susceptibility and specific heat measurements on a series of polycrystalline samples with controlled metal and oxygen contents. Because the Cu-O-Cu bonds are nearly orthogonal, holes are almost localized, and only spin degrees of freedom survive at low temperature. The results reveal that antiferromagnetic chains made of 50% spins per formula unit always exist, independent of spin density, and the remainder of spins mostly form dimers of variable density. A two-sublattice model is proposed by considering that the nearest-neighbor couplings are negligibly small, due to both geometrical frustration and the special Cu-O-Cu bond angle of ~95°. Thus next-nearest-neighbor interactions dominate, and give rise to a charge-ordered state on one sublattice, which behaves as a Heisenberg antiferromagnetic chain. The rest of the spins tend to form dimers on the other sublattice with low spin density. Long-range antiferromagnetic ordering appears to occur at 12 K.

本文言語English
ページ(範囲)1824-1833
ページ数10
ジャーナルjournal of the physical society of japan
69
6
DOI
出版ステータスPublished - 2000 6月
外部発表はい

ASJC Scopus subject areas

  • 物理学および天文学(全般)

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