Structural properties and magnetoresistance of La$_{1.952}$Sr$_{0.048}$CuO$_4$ thin films.

The evolution of the structural and transport properties of underdoped La$_{1.952}$Sr$_{0.048}$CuO$_4$ thin films under compressive epitaxial strain has been studied. The films of different thicknesses $d$ (from 26 nm to 120 nm) were deposited using an insulating target. The onset of superconductivity in the films is observed at temperatures as high as 26 K, while small residual resistance persists at low temperatures, indicating that superconductivity is inhomogeneous. The resistance measured under perpendicular magnetic field saturates below about 0.65 K, suggesting a possible existence of nonconventional metallic state. The magnetic-field-tuned superconductor-insulator transition is observed at magnetic field of about 32 T.