Аннотация:The electronic phase diagram of $R\mathrm{Co}{\mathrm{O}}_{3}$ ($R=\text{rare}$-earth) perovskites has been mapped out through high-pressure synthesis and heat capacity $({C}_{p})$ measurements. In contrast to $R=\mathrm{La}$ where the spin-state transition and insulator-metal transition each shows a broad ${C}_{p}$ anomaly, these anomalies merge into a large ${C}_{p}$ peak for smaller $R$. A detailed structural study employing synchrotron x-ray powder diffraction shows that the onset temperature for the spin-state transition is correlated with the ${\ensuremath{\sigma}}^{*}$-bonding ${e}_{g}$ bandwidth. A possible scenario on the spin state is provided to explain the ${C}_{p}$ anomaly and phase diagram.
Ключевые слова:Magnetic and transport properties of perovskites and related materials, Advanced Condensed Matter Physics, Thermal Expansion and Ionic Conductivity
