A common behavior of thermoelectric layered cobaltites: incommensurate spin density wave states in [Ca$_2$Co$_{4/3}$Cu$_{2/3}$O$_4$]$_{0.62}$[CoO$_2$] and [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$]

J. Sugiyama; J. H. Brewer; E. J. Ansaldo; H. Itahara; K. Dohmae; C. Xia; Y. Seno; B. Hitti; T. Tani

doi:10.1088/0953-8984/15/49/031

paper

A common behavior of thermoelectric layered cobaltites: incommensurate spin density wave states in [Ca $_{2}$ Co $_{4/3}$ Cu $_{2/3}$ O $_{4}$ ] $_{0.62}$ [CoO $_{2}$ ] and [Ca $_{2}$ CoO $_{3}$ ] $_{0.62}$ [CoO $_{2}$ ]

arXiv:cond-mat/0311161 · doi:10.1088/0953-8984/15/49/031

Abstract

Magnetism of a misfit layered cobaltite [Ca $_{2}$ Co $_{4/3}$ Cu $_{2/3}$ O $_{4}$ ] $_{x}^{RS}$ [CoO $_{2}$ ] ( $x \sim$ 0.62, RS denotes a rocksalt-type block) was investigated by a positive muon spin rotation and relaxation ( $μ^{+}$ SR) experiment. A transition to an incommensurate ({\sf IC}) spin density wave ({\sf SDW}) state was found below 180 K (= $T_{C}^{on}$ ); and a clear oscillation due to a static internal magnetic field was observed below 140 K (= $T_{C}$ ). Furthermore, an anisotropic behavior of the zero-field $μ^{+}$ SR experiment indicated that the {\sf IC-SDW} propagates in the $a$ - $b$ plane, with oscillating moments directed along the c axis. These results were quite similar to those for the related compound [Ca $_{2}$ CoO $_{3}$ ] $_{0.62}^{RS}$ [CoO $_{2}$ ], {\sl i.e.}, Ca $_{3}$ Co $_{4}$ O $_{9}$ . Since the {\sf IC-SDW} field in [Ca $_{2}$ Co $_{4/3}$ Cu $_{2/3}$ O $_{4}$ ] $_{0.62}^{RS}$ [CoO $_{2}$ ] was approximately same to those in pure and doped [Ca $_{2}$ CoO $_{3}$ ] $_{0.62}^{RS}$ [CoO $_{2}$ ], it was concluded that the {\sf IC-SDW} exist in the [CoO $_{2}$ ] planes.

15 pages, 6 figures. accepted for publication in J. Phys.: Condens. Matter

A common behavior of thermoelectric layered cobaltites: incommensurate spin density wave states in [Ca2​Co4/3​Cu2/3​O4​]0.62​[CoO2​] and [Ca2​CoO3​]0.62​[CoO2​]

Abstract

A common behavior of thermoelectric layered cobaltites: incommensurate spin density wave states in [Ca $_{2}$ Co $_{4/3}$ Cu $_{2/3}$ O $_{4}$ ] $_{0.62}$ [CoO $_{2}$ ] and [Ca $_{2}$ CoO $_{3}$ ] $_{0.62}$ [CoO $_{2}$ ]