Effect of spacer layer thickness on magnetic and electrical properties of La/sub 0.7/Sr/sub 0.3/MnO/sub 3//SrTiO/sub 3/ superlattices

Abstract

The effects of spacer layer (SrTiO/sub 3/) thickness on the magnetic and electrical properties of La/sub 0.7/Sr/sub 0.3/MnO/sub 3//SrTiO/sub 3/ superlattices has been studied by fabricating a series of multilayers on SrTiO/sub 3/ [100] substrates by pulsed laser deposition. High quality of the films was ensured by X-ray diffraction and transmission electron microscopy. All studied films are ferromagnetic below a transition temperature T/sub C/. The T/sub C/ as well as saturation magnetization M/sub S/ depend on the thickness of SrTiO/sub 3/. However, these dependences are nonmonotonic. The electrical resistivity is metallic-like below 300 K. The magnetoresistance measured at 20 K has been found to depend on the SrTiO/sub 3/ thickness and correlates with the magnetic measurements. The results are discussed in terms of surface corrugation due to epitaxial strain, surface dead-layer concept, and interlayer coupling.