Superconducting Properties and Phase Diagram of Indirectly Electron-Doped $(\hbox{Sr}_{1 - x}\hbox{La}_{x})\hbox{Fe}_{2}\hbox{As}_{2}$ Epitaxial Films Grown by Pulsed Laser Deposition

A nonequilibrium phase (Sr
_1-x
La
_x
)Fe
₂
As
₂
was formed by epitaxial film-growth. The resulting films emerged superconductivity along with suppression of the resistivity anomaly, which is associated with magnetic and structural phase transitions. The maximum critical temperature was 20.8 K, which is almost the same as that of directly electron-doped Sr(Fe
_1-x
Co
_x
)
₂
As
₂
. Its electronic phase diagram is much similar to that of Sr( Fe
_1-x
Co
_x
)
₂
As
₂
, indicating that the difference in the electron doping sites does not influence the superconducting properties of 122-type SrFe
₂
As
₂
.