Early stage spin-state transition in LaCoO3 investigated by first principles
Abstract
Thermal-induced spin-state transition in LaCoO3 has been a highly debated phenomenon. The point in controversy is whether the intermediate-spin (IS) state can stably exist, and whether the intermediate-spin or high-spin (HS) state is the first excited state. In our calculation, we have successfully stabilized isolated HS and IS Co in an array of low-spin (LS) Co in LaCoO3 using the local density approximation + Hubbard U (LDA+U) method. The HS/LS (or IS/LS) Co population ratio is set to 1:7, so that the early stage of spin-state transition is properly approximated. The Hubbard U is self-consistently determined by first principles, so that the equation of state and the energy of Co in each spin state can be determined with better accuracy. We show that at low temperature, isolated IS Co has higher energy than isolated HS Co. We also show that low concentration of isolated IS Co can lead to metallic LaCoO3. Therefore, the early stage spin-state transition in LaCoO3 is LS-to-HS transition. This work was supported primarily by the MRSEC Program of the National Science Foundation under Award Number DMR-0212302 and DMR-0819885. It was also partially supported by NSF grants ITR-0426757 (VLab) and EAR 0757903. Calculations were performed at Minnesota Supercomputing Institute (MSI).
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMMR31A1636L
- Keywords:
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- 3919 MINERAL PHYSICS / Equations of state