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Effect of light Sr doping on the spin-state transition in LaCoO_3

A. Podlesnyak·K. Conder·E. Pomjakushina·A. Mirmelstein·P. Allenspach·D. I. Khomskii
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Abstract

We present an inelastic neutron scattering study of the low energy crystal-field excitations in the lightly doped cobalt perovskite La_0.998Sr_0.002CoO_3. In contrast to the parent compound LaCoO_3 an inelastic peak at energy transfer ~0.75 meV was found at temperatures below 30 K. This excitation apparently corresponds to a transition between a ground state orbital singlet and a higher excited orbital doublet, originating from a high-spin triplet split by a small trigonal crystal field. Another inelastic peak at an energy transfer ~0.6 meV was found at intermediate temperatures starting from T > 30 K. This confirms the presence of a thermally induced spin-state transition from the low-spin Co^3+ to a magnetic high-spin state in the non-disturbed LaCoO_3 matrix. We suggest that hole doping of LaCoO_3 leads to the creation of a magnetic polaron and hence to the low-to-high spin state transition on the relevant Co sites.

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A. Podlesnyak, K. Conder, E. Pomjakushina, A. Mirmelstein, P. Allenspach, D. I. Khomskii. 2006-09-11. Effect of light Sr doping on the spin-state transition in LaCoO_3. https://doi.org/10.1016/j.jmmm.2006.10.901

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