Four dimensional-scanning transmission electron microscopy study on relationship between crystallographic orientation and spontaneous polarization in epitaxial BiFeO.

Spontaneous polarization and crystallographic orientations within ferroelectric domains are investigated using an epitaxially grown BiFeO thin film under bi-axial tensile strain. Four dimensional-scanning transmission electron microscopy (4D-STEM) and atomic resolution STEM techniques revealed that the tensile strain applied is not enough to cause breakdown of equilibrium BiFeO symmetry (rhombohedral with space group: R3c). 4D-STEM data exhibit two types of BiFeO ferroelectric domains: one with projected polarization vector possessing out-of-plane component only, and the other with that consisting of both in-plane and out-of-plane components.

Formation of Brightly Luminescent MoS Nanoislands from Multilayer Flakes via Plasma Treatment and Laser Exposure.

A robust and reliable method for enhancing the photoluminescence (PL) of multilayer MoS is demonstrated using an oxygen plasma treatment process followed by laser exposure. Here, the plasma and laser treatments result in an indirect-to-direct band gap transition. The oxygen plasma creates a slight decoupling of the layers and converts some of the MoS to MoO.