Dynamic Vortex Phases and Pinning in Superconductors with Twin Boundaries

We investigate the pinning and driven dynamics of vortices interacting with twin boundaries using large scale molecular dynamics simulations on samples with near one million pinning sites. For low applied driving forces, the vortex lattice orients itself parallel to the twin boundary and we observe the creation of a flux gradient and vortex free region near the edges of the twin boundary. For increasing drive, we find evidence for several distinct dynamical flow phases which we characterize by the density of defects in the vortex lattice, the microscopic vortex flow patterns, and orientation of the vortex lattice. We show that these different dynamical phases can be directly related to microscopically measurable voltage - current V(I) curves and voltage noise. By conducting a series of simulations for various twin boundary parameters we derive several vortex dynamic phase diagrams.Comment: 5 figures, to appear in Phys. Rev.

Metastable Phases in Rapidly Solidified Aluminum-Rich Al-Fe Alloys

ABSTRACTAluminum-rich Al-Fe binary alloys up to and including Al3Fe were prepared by melt spinning in order to study the metastable phase structure and its transformation following heat treatment. Transmission electron microscopy and nuclear gamma-ray resonance were utilized in the study. The rapidly solidified structure was found to contain up to three metastable phases. One of the phases, with a composition and a gamma-ray resonance spectrum appropriate for Al6Fe, has either a globular or a cellular morphology upon quenching.</jats:p

A flexible least squares routine for general Mössbauer effect spectra fitting

Title of program: FLEXIBLE MOSSBAUER FIT ROUTINE Catalogue Id: ACML_v1_0 Nature of problem A general program is presented to fit experimental Mossbauer data to theoretical functions. The program is designed to allow the theoretical function to be easily changed. Versions of this program held in the CPC repository in Mendeley Data ACML_v1_0; FLEXIBLE MOSSBAUER FIT ROUTINE; 10.1016/0010-4655(74)90005-8 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019