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arXiv · 2001.05194

Evolution of valence-specific spin states and local distortions in La$_{2-x}$Sr$_x$CoO$_4$

J. Okamoto·A. Chainani·Z. Y. Chen·H. Y. Huang·A. Singh·T. Sasagawa·D. I. Khomskii·A. Fujimori·C. T. Chen·D. J. Huang
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Abstract

We present X-ray spectroscopic evidence for the evolution of valence-specific spin states and tetragonal distortions in single-layer cobaltates. Measurements of Co $L_3$-edge resonant inelastic X-ray scattering reveal the $t_{2g}$ electronic structure of Co for hole-doped La$_{2-x}$Sr$_x$CoO$_4$ ($x$ = 0.5, 0.7 and 0.8). As the Sr-doping $x$ increases, the tetragonal splitting of the $t_{2g}$ states of high-spin Co$^{2+}$ decreases, whereas that of low-spin Co$^{3+}$ increases and the fraction of high-spin Co$^{3+}$ increases. The results enable us to clarify the origin of the change of magnetic anisotropy and in-plane resistivity in a mixed-valence cobaltate caused by the interplay of spin-orbit coupling and tetragonal distortion.

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J. Okamoto, A. Chainani, Z. Y. Chen, H. Y. Huang, A. Singh, T. Sasagawa, D. I. Khomskii, A. Fujimori, C. T. Chen, D. J. Huang. 2020-01-15. Evolution of valence-specific spin states and local distortions in La$_{2-x}$Sr$_x$CoO$_4$. https://doi.org/10.1103/physrevb.104.054417

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