Pressure effect on the double-exchange ferromagnet ${\mathrm{La}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{MnO}}_3$ (0.15≤x≤0.5)

The effect of hydrostatic pressure on the magnetic and electronic properties has been investigated for prototypical double-exchange ferromagnets, ${\mathrm{La}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Sr}}_{\mathit{x}}$ ${\mathrm{MnO}}_3$, with varying nominal hole concentration x (0.15≤x≤0.5). A pressure-enhanced transfer interaction is observed to stabilize the ferromagnetic metallic phase, i.e., increase the Curie temperature ${\mathit{T}}_{\mathit{C}}$, over the whole concentration range investigated. The pressure coefficient of ${\mathit{T}}_{\mathit{C}}$ is found to be significantly x dependent and steeply decreases from d ln${\mathit{T}}_{\mathit{C}}$/dP≊+0.065 ${\mathrm{GPa}}^{\mathrm{-}1}$ at x=0.15 to a small value (≊+0.005 ${\mathrm{GPa}}^{\mathrm{-}1}$) at x=0.4–0.5. This suggests a symptomatic change of the electronic nature from the strong- to weak-coupling region with increasing the hole-doping level.