Search

We have compared the multiferroic behavior in different-sized BiFeO nanoparticles (11-29 nm) prepared by a solution evaporation method. The effects of oxygen vacancies on the behavior of phase pure BiFeO have been studied for particles prepared under two different annealing environments, air and oxygen. We find that BiFeO nanoparticles show weak ferromagnetism at room temperature which increases with decreasing particle size. However, the effects are determined not to be related to the presence of more oxygen vacancies, since oxygen annealing increases the magnetic moment in this system. In dielectric studies, we observe clear evidence for magnetoelectric coupling with the imaginary part of dielectric constant exhibiting a clear anomaly around the magnetic transition temperature ( T ~ 560 K). In high temperature resistivity measurements insulating and activated resistivity behavior is observed with the activation energies being lower for T < T. The increased ferromagnetism in smaller particles is explained in terms of suppression of the antiferromagnetic spin spiral whereas oxygen annealing actually leads in our case to an improvement of the crystallinity. [ABSTRACT FROM AUTHOR]

Abstract: The misunderstanding of the labeling for an “MR conditional” respiratory ventilator system resulted in the placement of this device, which had substantial ferromagnetic components, too close to a 3-T magnetic resonance (MR) system, causing a projectile incident. Magnetic resonance imaging health care professionals should be aware of the potentially dangerous consequences when such medical devices that have Food and Drug Administration-approved MR conditional labeling are brought into the MR system room. Recommendations to prevent future incidents are provided herein. [Copyright &y& Elsevier]

Abstract: A paleomagnetic study of subsurface core samples from dolomitized carbonates of two producing reservoirs in the Upper Ordovician Trenton Formation, collected from four wells in southwestern Ontario yielded a paleomagnetic direction of D =152.3°, I =−12.3° (N =49, α 95 =8.7). This characteristic remanent magnetization (ChRM) direction was azimuth-corrected by aligning the viscous remanence magnetization (VRM) with the present Earth''s magnetic field direction. A drilling-induced magnetization (VRMdi) was present in less than half the specimens sampled in this study. In addition, where the VRM correction could not be made, a paleolatitudinal arc calculated from the inclination-only mean of I =−9.0° (N =34, α 95 =3.0°) intersected the apparent polar wander path in the Late Permian–Early Triassic. These paleodirections are similar to the paleomagnetic directions observed in Ordovician Trenton carbonates from the Michigan Basin and New York State, U.S.A., suggesting a related regional late Paleozoic remagnetization. [Copyright &y& Elsevier]

Three sections of Chesterian Mauch Chunk Formation in Pennsylvania have been studied paleomagnetically to determine a Late Mississippian magnetic polarity stratigraphy. The upper section at Lavelle includes a conglomerate with abundant red siltstone rip-up clasts that yielded a positive conglomerate test. All samples were subjected to progressive thermal demagnetization to temperatures as high as 700°C. Two components of magnetization were isolated: a synfolding "B" component and the prefolding "C" component. The conglomerate test is positive, indicating that the C component was acquired very early in the history of the sediment. A coherent pattern of magnetic polarity reversals was identified. Five magnetozones were identified in the upper Lavelle section, which yields a pattern that is an excellent match with the pattern of reversals obtained from the upper Mauch Chunk at the original type section of the Mississippian/Pennsylvanian boundary at Pottsville, PA. The frequency of reversals in the upper Mississippian, as identified in the Mauch Chunk Formation, is approximately one to two per million years, which is an average for field reversal through time. [ABSTRACT FROM AUTHOR]

An interview with Scott Chambers is presented. When asked of when he became concerned on epitaxial oxide films, he mentions the time when he was invited to join to Pacific Northwest National Laboratory as a head of a research initiative. He states that there are still better tools in elucidating ferromagnetism's origin. When asked of the importance of growth conditions, he explains that it can determine the sufficiency of oxygen fugacity.