Low-energy planar magnetic defects in BaFe2As2: Nanotwins, twins, antiphase, and domain boundaries

Ferroelectric translational antiphase boundaries in nonpolar materials

Ferroelectric materials are heavily used in electro-mechanics and electronics. Inside the ferroelectric, domain walls separate regions in which the spontaneous polarization is differently oriented. Properties of ferroelectric domain walls can differ from those of the domains themselves, leading to new exploitable phenomena. Even more exciting is that a non-ferroelectric material may have domain...

Antiphase domain boundaries in the superconducting phase of the Y-Ba-Cu-O system.

Antiphase magnetic boundaries in iron-based superconductors: A first-principles density-functional theory study

Superconductivity arises in the layered iron-pnictide compounds when magnetic long-range order disappears. We use first-principles density-functional methods to study magnetic arrangements that may compete with long-range order near the phase boundary. Specifically, we study the energetics and charge-density distribution through calculation of the electric field gradients for ordered supercells...

Magnetic Excitation and Thermodynamics of BaFe2As2

Magnetic excitation of the iron-based superconductor parent compound BaFe2As2 at finite temperature are addressed with a first-principles formulation of the Helmholtz energy, which can account for the finite temperature mixture of many magnetic configurations. We find that it is the spin exchange coupling in the interplane c direction that dictates the spin density wave ordering. We have also q...

Low-energy, Mobile Grain Boundaries in Magnesium

The strong basal texture that is commonly developed during the rolling of magnesium alloy and can even increase during annealing motivates atomic-level study of dislocation structures of both <0001> tilt and twist grain boundaries (GBs) in Magnesium. Both symmetrical tilt and twist GBs over the entire range of rotation angles θ between 0° and 60° are found to have an ordered atomic structure an...