Wenyi Tan

Characterization of surface and interface structure of YBa2Cu3O7−δ-based trilayer with La0.67Ca0.33MnO3 spacer

Thin YBa2Cu3O7-delta/La0.67Ca0.33MnO3/YBa2Cu3O7-delta (YBCO/LCMO/YBCO) trilayers on (001)-oriented SrTiO3 (STO) substrates were fabricated by magnetron sputtering technique. The trilayers are well c-axis oriented confirmed by x-ray diffraction. The surface and interface structure of the trilayers were investigated by grazing incident x-ray reflectivity. The results showed that there exists diffusion at the YBCO/LCMO interfaces with the diffusion length of several nanometers. The root-mean-square (rms) roughness of surface and interface in the trilayers varied with the thickness of YBCO layer. The rms roughness of surface was consistent with observation by atomic force microscopy. A further analysis indicated that the rms roughness was correlative to the misfit strain relaxation in film

Grain-boundary effects on magnetotransport properties in La2∕3Ca1∕3MnO3∕YBa1.8Eu0.2Cu3O7 multilayers

La2∕3Ca1∕3MnO3 (LCMO)/YBa1.8Eu0.2Cu3O7 (YBECO) multilayers on yttrium-stabilized ZrO2 are fabricated. YBECO sublayer is well crystallized in c-axis orientation, while LCMO sublayer crystallized in (001) textured structure, which forms special mosaic structure. By magnetization measurements, we confirm that the cluster spin glass existed in LCMO/YBECO multilayers in low temperature, which may scatter the transport electrons. Superconductivity cannot be observed when thickness of YBECO layer is less than 24nm. The magnetoresistance ratio depends on the thickness of YBECO layer. The magnetotransport properties of the multilayers make it very promising to provide a technological support for the heterostructure and superlattice of manganites and superconductors.