Ferromagnetism and large negative magnetoresistance in Pb doped Bi-Sr-Co-O misfit-layer compound

I. Tsukada; T. Yamamoto; M. Takagi; T. Tsubone; S. Konno; K. Uchinokura

doi:10.1143/JPSJ.70.834

paper

Ferromagnetism and large negative magnetoresistance in Pb doped Bi-Sr-Co-O misfit-layer compound

arXiv:cond-mat/0012395 · doi:10.1143/JPSJ.70.834

Abstract

Ferromagnetism and accompanying large negative magnetoresistance in Pb-substituted Bi-Sr-Co-O misfit-layer compound are investigated in detail. Recent structural analysis of (Bi,Pb) $_{2}$ Sr $_{3}$ Co $_{2}$ O $_{9}$ , which has been believed to be a Co analogue of Bi $_{2}$ Sr $_{2}$ CaCu $_{2}$ O $_{8 + δ}$ , revealed that it has a more complex structure including a CoO $_{2}$ hexagonal layer [T. Yamamoto {\it et al.}, Jpn. J. Appl. Phys. {\bf 39} (2000) L747]. Pb substitution for Bi not only introduces holes into the conducting CoO $_{2}$ layers but also creates a certain amount of localized spins. Ferromagnetic transition appears at $T$ = 3.2 K with small spontaneous magnetization along the $c$ axis, and around the transition temperature large and anisotropic negative magnetoresistance was observed. This compound is the first example which shows ferromagnetic long-range order in a two-dimensional metallic hexagnonal CoO $_{2}$ layer.

8 pages including eps figures. To be published in J. Phys. Soc. Jpn

Ferromagnetism and large negative magnetoresistance in Pb doped Bi-Sr-Co-O misfit-layer compound

Abstract

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