Pressure- and temperature-induced spin-state transition in single-crystalline La_1−xSr_xCoO₃(x=0.10and 0.33)

Abstract

We report on the temperature dependence of magnetization (M) and resistivity (rho) of La1−xSrxCoO3(x=0.10and 0.33) (x=0.10 and 0.33) single crystals. For x=0.10, the temperature dependence of field-cooled magnetization (M-FC) and zero-field-cooled magnetization (M-ZFC) are similar to that expected for a canonical spin-glass system. The thermal response of M-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 (P) for the metallic sample (x=0.33) while the dependence of rho on P for the insulating sample (x=0.10) is quite complicated; the pressure coefficient of resistivity (d rho/dT) 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 (P>5.4 GPa) and high temperatures (T>110 K).