Pressure- and temperature-induced spin-state transition in single-crystallineLa1−xSrxCoO3(x=0.10and 0.33)

We report on the temperature dependence of magnetization $\left(M\right)$ and resistivity $\left(\rho \right)$ of ${\text{La}}_{1-x}{\text{Sr}}_x{\text{CoO}}_3$ ($x=0.10$ and 0.33) single crystals. For $x=0.10$, the temperature dependence of field-cooled magnetization $\left(M_{\text{FC}}\right)$ and zero-field-cooled magnetization $\left(M_{\text{ZFC}}\right)$ are similar to that expected for a canonical spin-glass system. The thermal response of $M_{\text{ZFC}}$ for $x=0.33$ indicates a glassy ferromagnetic state. We observe that the ferromagnetic transition temperature $T_C$ decreases and $\rho$ increases rapidly with increasing pressure $\left(P\right)$ for the metallic sample $\left(x=0.33\right)$ while the dependence of $\rho$ on $P$ for the insulating sample $\left(x=0.10\right)$ is quite complicated; the pressure coefficient of resistivity $\left(d\rho /dT\right)$ is sensitive to temperature and applied pressure due to the strong interplay between the pressure-induced band broadening and spin-state transition phenomenon. $d\rho /dT$ is large and negative at low-pressure and low-temperature regimes while small and positive at high pressures $\left(P>5.4\text{GPa}\right)$ and high temperatures $\left(T>110\text{K}\right)$.