Transport and magnetic properties ofLa1−xBaxCoO3

Abstract

We have systematically investigated transport, magnetic, and structural properties of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ba}}_{x}{\mathrm{CoO}}_{3}$ in the range of doping $0lx\ensuremath{\leqslant}0.55$. In this system, the metal-insulator transition is observed to be coincident with the onset of ferromagnetic (FM) ordering at $x=0.20$. Well below Curie temperature ${T}_{C}$, $\ensuremath{\rho}$ exhibits ${T}^{2}$ behavior whereas over a temperature interval just below ${T}_{C}$, it shows ${T}^{4}$ dependence due to the scattering of charge carriers by magnetic fluctuations. For $xl0.20$, the low temperature magnetic property is dominated by a spin-glass- or cluster-glasslike phase. The role of ionic size mismatch on the above mentioned physical properties has also been investigated by partially substituting $\mathrm{La}$ with $\mathrm{Nd}$ and $\mathrm{Ba}$ with $\mathrm{Sr}$ for a fixed doping. A phase diagram, the dependence of transition temperatures on doping $(x)$, has been constructed for ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ba}}_{x}{\mathrm{CoO}}_{3}$ from this study.