Stabilization of Sr-rich ultrathin epitaxial films of La2-xSrxCuO4

Varying the level of Sr in La2-xSrxCuO4 produces a wide array of electrical properties, spanning metallic, semiconducting, insulating, and superconducting. While the system has been extensively studied, ultrathin films with high Sr content have not been reported. Using oxide molecular beam epitaxy, ultrathin La2-xSrxCuO4 films (0 < x < 1) were grown to explore the ability to stabilize high Sr content in such films. The resulting crystallinity, surface roughness, and electrical properties of the samples are studied. The films are single crystalline with low surface roughness. Increasing the Sr content from x = 0 to x = 1.0 causes an initial increase and subsequent decrease in the c-axis lattice parameter and the surface roughness as a function of doping. The films exhibit analogous electrical properties to their bulk and thicker film counterparts. The ability to create ultrathin La2-xSrxCuO4 films at high Sr levels shows promise for inducing unexpected electric properties through dopant modulation effects, such as cation ordering, digital superlattices, and atomically precise interfaces.