Structural and compositional characterization of a Co∕Re multilayer and superlattice

Abstract

Structural, magnetotransport, and micromagnetic properties of sputtered Ir(111)/Co superlatticesThe structure and composition of a Co/ Re trilayer and a 19-period superlattice were characterized by high-resolution transmission electron microscopy ͑TEM͒ and scanning TEM ͑STEM͒. Low-angle x-ray reflectivity measurements were performed and compared with the TEM results. The Re and Co layers are epitaxial with their ͑1010͒ planes parallel to the ͑1120͒ plane of Al 2 O 3 , and the ͓001͔ direction of Re and Co layers coincides with that of the Al 2 O 3 . The in-plane lattice parameters for Co, Re, and Al 2 O 3 are approximately 0.24 and 0.43 nm, 0.26 and 0.44 nm, and 0.24 and 0.44 nm, respectively, in the superlattice. The lattice spacing of Al 2 O 3 corresponds to a / 2 and c / 3, where a and c are lattice parameters of the Al 2 O 3 . High-angle and low-angle annular-dark-field STEM and nanoscale electron energy loss spectroscopy line analysis exhibit very weak interdiffusion between Co and Re layers; therefore, very sharp interfaces are maintained in the superlattice. The initial interface roughness between the Re buffer layer and the first Co layer is amplified during the subsequent growth of the superlattices. Layer thickness fluctuations are much smaller in the Re/ Co superlattice than the interface roughness, which suggests that interface roughness plays a more important role in the giant magnetoresistance effect than thickness fluctuations of the spacer layer.

Cation ordering within the perovskite block of a six-layer Ruddlesden-Popper oxide from layer-by-layer growth – artificial interfaces in complex unit cells

“…The calculation used is based on path-length calculations of interference in thin films. [50][51][52][53] A similar value (81 AE 2 nm) for the thickness was obtained from the Fast Fourier Transform (FFT) of the data. 54 The data were fit using the segmented fit algorithm.…”