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arXiv · 2108.00481

Cobalt in strontium titanate as a new off-center magnetic impurity

I. A. Sluchinskaya·A. I. Lebedev
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Abstract

The local structure and oxidation state of the cobalt impurity in SrTiO$_3$ is studied by X-ray absorption fine structure (XAFS) spectroscopy. The synthesis conditions, under which cobalt predominantly (up to 76%) substitutes the atoms at the $A$ site of the perovskite structure, is found for SrTiO$_3$(Co) samples. By varying the synthesis conditions, it is possible to appreciably change the ratio between the concentrations of cobalt atoms incorporated into the $A$ and $B$ sites. It is established that the oxidation state of cobalt is +2 at the $A$ site and +3 at the $B$ site. It is revealed that the Co impurity at the $A$ site is off-center, and its displacement from the lattice site is $\sim$1.0 {\AA}. First-principles calculations show that an isolated Co$^{3+}$ ion at the $B$ site is diamagnetic, whereas the Co$^{2+}$ ion at the $A$ site is in a high-spin state ($S = 3/2$).

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I. A. Sluchinskaya, A. I. Lebedev. 2021-08-01. Cobalt in strontium titanate as a new off-center magnetic impurity. https://doi.org/10.1134/s1063783419030302

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