Novel electronic states realized by the interplay between Li diffusion and Co$^{\rm 3+}$$/$Co$^{\rm 4+}$ charge ordering in Li$_{\rm x}$CoO$_2$

Kiyotaka Miyoshi; Kentaro Manami; Ryo Sasai; Shijo Nishigori; Jun Takeuchi

doi:10.1103/PhysRevB.98.195106

paper

Novel electronic states realized by the interplay between Li diffusion and Co $^{3 +}$ $/$ Co $^{4 +}$ charge ordering in Li $_{x}$ CoO $_{2}$

arXiv:1808.08010 · doi:10.1103/PhysRevB.98.195106

Abstract

Measurements of dc magnetization ( $M$ ) and electrical resistivity ( $ρ$ ) have been carried out as a function of temperature ( $T$ ) for layered oxide Li $_{x}$ CoO $_{2}$ (0.51 $\leq$ $x$ $\leq$ 1.0) using single crystal specimens. After slow cool of the specimens down to 10 K, both of the $M$ ( $T$ ) and $ρ$ ( $T$ ) curves are found to exhibit a clear anomaly due to the occurrence of Co $^{3 +}$ $/$ Co $^{4 +}$ charge ordering (CO) at $T_{S}$ $\sim$ 155 K for 0.6 $\leq$ $x$ $\leq$ 0.98 (at $T_{S}$ $\sim$ 180 $-$ 190 K for 0.5 $\leq$ $x$ $\leq$ 0.55). After rapid cool of the specimens, additional anomalies are observed related to the onset of Li diffusion at $T_{F1}$ $\sim$ 370 K and $/$ or $T_{F2}$ =120 $-$ 130 K. Due to phase mixing with compositions of nearly LiCoO $_{2}$ and Li $_{2/3}$ CoO $_{2}$ , the specimens with 0.7 $≲$ $x$ $≲$ 0.9 show anomlies both at $T_{F1}$ and $T_{F2}$ . For 0.6 $≲$ $x$ $≲$ 0.9, the resistivity measured after rapid cool is found to be fairly larger than that measured after slow cool below $T_{S}$ . The enhanced resistivity can be explained by the scenario that disordered Co $^{3 +}$ $/$ Co $^{4 +}$ arrangements, which have been observed and revealed to have an insulating electronic structure contrasting to the regular CO state in the previous scanning tunneling microscopy measurements [Phys. Rev. Lett. {\bf 111}, 126104 (2013)], are realized due to the formation of an amorphous-like structure of Li ions after rapid cool via the interlayer Coulomb coupling. An electronic phase diagram for 0.5 $\leq$ $x$ $\leq$ 1.0 is proposed.

arXiv comment8 pages, 5 figures, to appear in Phys. Rev. B

Novel electronic states realized by the interplay between Li diffusion and Co $^{3 +}$ $/$ Co $^{4 +}$ charge ordering in Li $_{x}$ CoO $_{2}$

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Novel electronic states realized by the interplay between Li diffusion and Co3+/Co4+ charge ordering in Lix​CoO2​

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Cited by in corpus (4)

Novel electronic states realized by the interplay between Li diffusion and Co $^{3 +}$ $/$ Co $^{4 +}$ charge ordering in Li $_{x}$ CoO $_{2}$