Physical properties of Cu/La0.67Ba0.33MnO3/SrTiO3 : Nb junctions with ultrathin manganite layers

We performed a systematic study on a Cu/La0.67Ba0.33MnO3/SrTiO3 : Nb (Cu/LBMO/STON) junction with a manganite layer, a few unit cells in width, focusing on the evolution of Cu-STON coupling as the film thickness of LBMO grew. The physical properties of the junction are found to be jointly determined by the electrode, the film and the substrate when the film thickness of LBMO is below similar to 1 nm, with a carrier tunnelling process and a weakly rectifying feature. A LBMO film above similar to 1 nm completely screens the electrode-substrate interaction, enhancing the rectifying character of the junctions significantly. A further increase in film thickness leads only to a minor modification of the junctions.