Nanoscale insight into the statics and dynamics of polarization behavior in thin film ferroelectric capacitors

In this study, we review recent advances in PFM studies of micrometer scale ferroelectric capacitors, summarize the experimental PFM-based approach to investigation of fast switching processes, illustrate what information can be obtained from PFM experiments on domains kinetics, and delineate the scaling effect on polarization reversal mechanism. Particular attention is given to PFM studies of mechanical stress effect on polarization stability.

Continuous/Cluster-Pinned Recording Media

We propose and theoretically investigate a new class of nanostructured magnetic recording films, cluster-pinned recording media. The films consist of magnetic clusters exchange coupled to a continuous hard layer with perpendicular anisotropy and low coercivity. Our calculations yield the coercivity and the cross-track correlation length as a function of film thickness and pinning density and strength. The mechanism is very similar to the Gaunt–Friedel pinning in bulk magnets, which differs from ordinary strong pinning by the selfconsistent dependence of wall curvature and coercivity on defect concentration. The main difference is the exponent for the coercivity as a function of the pinning strength, which is equal to 2 in the bulk but equal to 3/2 in thin films. The pinning strength is estimated for various regimes, and it is shown that the diminished domain-wall curvature reduces jitter.

Growth and Characterization of Silicon Carbide Thin Films Using a Nontraditional Hollow Cathode Sputtering Technique

Silicon carbide (SiC) is considered a suitable candidate for high-power, high-frequency devices due to its wide bandgap, high breakdown field, and high electron mobility. It also has the unique ability to synthesize graphene on its surface by subliming Si during an annealing stage. The deposition of SiC is most often carried out using chemical vapor deposition (CVD) techniques, but little research has been explored with respect to the sputtering of SiC. Investigations of the thin film depositions of SiC from pulse sputtering a hollow cathode SiC target are presented. Although there are many different polytypes of SiC, techniques are discussed that were used to identify the film polytype on both 4H-SiC substrates and Si substrates. Results are presented about the ability to incorporate Ge into the growing SiC films for the purpose of creating a possible heterojunction device with pure SiC. Efforts to synthesize graphene on these films are introduced and reasons for the inability to create it are discussed. Analysis mainly includes crystallographic and morphological studies about the deposited films and their quality using x-ray diffraction (XRD), reflection high energy electron diffraction (RHEED), transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), Auger electron spectroscopy (AES) and Raman spectroscopy. Optical and electrical properties are also discussed via ellipsometric modeling and resistivity measurements. The general interpretation of these analytical experiments indicates that the films are not single crystal. However, the majority of the films, which proved to be the 3C-SiC polytype, were grown in a highly ordered and highly textured manner on both (111) and (110) Si substrates.

Stability of Order in Solvent-Annealed Block Copolymer Thin Films

ABSTRACT: One way to produce high order in a block copolymer thin film is by solution casting a thin film and slowly evaporating the solvent in a sealed vessel. Such a solvent-annealing process is a versatile method to produce a highly ordered thin film of a block copolymer. However, the ordered structure of the film degrades over time when stored under ambient conditions. Remarkably, this aging process occurs in mesoscale thin films of polystyrene-polyisoprene triblock copolymer where the monolayer of vitrified 15 nm diameter polystyrene cylinders sink in a 20 nm thick film at 22 °C. The transformation is studied by atomic force microscopy (AFM). We describe the phenomena, characterize the aging process, and propose a semiquantitative model to explain the observations. The residual solvent effects are important but not the primary driving force for the aging process. The study may lead to effective avenue to improve order and make the morphology robust and possibly the solvent-annealing process more effective.

RB32-266 Cooling Milk on Nebraska Farms

The desire of Nebraska people to continue the improvement of living conditions and to secure more healthful foods has been responsible for many changes in methods of caring for milk. One of the important factors in keeping milk sweet and of good quality is the process of cooling and keeping it cool until used. Three of these processes are as follows: placing containers of warm milk in any quantity of still water or still air at temperatures ranging from freezing to within a few degrees of the temperature of the milk, placing the containers in such positions that air or water are circulated around them, and causing the milk to flow in such manner that a thin film comes in contact with a surface which is cooled by air or liquids varying in temperature from 10 degrees Fahrenheit to a few degrees below that of the milk. After some of the heat has been removed the milk is stored under conditions very similar to those found in cooling processes. This 1932 research bulletin discusses why milk is cooled, why milk sours, how bacteria grows, and the many ways that milk can be cooled.