ABSTRACT
The accuracy and precision of thin-film interfacial mixing as measured with atom probe tomography (APT) are assessed by considering experimental and simulated field-evaporation of a Co/Cu/Co multilayer structure. Reconstructions were performed using constant shank angle and Z-scale reordering algorithms. Reconstruction of simulated data (zero intermixing) results in a 10-90% intermixing width of ~0.2 nm while experiential intermixing (measured from multiple runs) was 0.47 ± 0.19 and 0.49 ± 0.10nm for Co-on-Cu and Cu-on-Co interfaces, respectively. The experimental data were collected in analysis orientations both parallel and anti-parallel to film growth direction and the impact of this on the interfacial mixing measurements is discussed. It is proposed that the resolution of such APT measurements is limited by the combination of specimen shape and reconstruction algorithms rather than by an inherent instrumentation limit.
ABSTRACT
This paper describes a novel technique for studying structure-transport correlations in nanoscale multilayer thin films. Here, local current-voltage characteristics from simplified magnetic tunnel junctions are measured in situ on cross-sectional transmission electron microscopy (TEM) samples and correlated directly with TEM images of the microstructure at the tunneling site. It is found that local variations in barrier properties can be detected by a point probe method, and that the tunneling barrier height and width can be extracted.
ABSTRACT
We report on experiments of light transmissivity, at wavelengths of 532 nm and 400 nm, through an Au film with a wedge shape. Our results exhibit a resemblance with those reported for observing negative refraction in proposed left-handed materials. This resemblance is present even though the medium that we used is well known to be right handed with its refractive index, therefore, having a positive real part. Analogous results are obtained with a glass wedge at 320 nm where absorption dominates. The experiment is explained by the wave losses that dominate over propagation, as in the already reported observation of negative refraction in developed metamaterial wedges. We design and propose an experiment with metamaterials by using thicker wires and parallel face slabs, in correspondence with light measurements that we have carried out in positive refractive index samples. This experimental configuration should conclusively determine whether refraction is positive or negative.
ABSTRACT
We show that ballistic magnetoresistance exhibits universal scaling in atomic or nanometer scale contacts. Plotting the data as conductance, we find that, if the maximum magnetoconductance is normalized to unity and the conductance is scaled with the conductivity of the bulk material, the data fall in a narrow region, independent of the nanocontact materials, for our four data sets and four from the literature. The results agree with a theory that takes into account spin-scattering within a magnetic-domain wall.
