An Investigation of Some Parameters which Influence the Magnetic Characteristics of Ferrites

Master's Thesis Proposal: An Investigation of Some Parameters which Influence the Magnetic Characteristics of Ferrites. Recent theories have been advanced concerning the squareness of the hysteresis loop and the dynamics of the magnetic switching mechanism in polycrystalline ferrites. These theories require evaluation. The important parameters of these theories, grain-to-grain alignment of the direction of magnetization, domain-wall energy density, and the saturation moment, will be investigated in this thesis

Magnetostriction in Ferrites Possessing a Square Hysteresis Loop

The development of ceramic materials with an intrinsically square hysteresis loop for use as storage elements in high-speed electronic computers has been largely empirical. A fundamental understanding of the basic mechanism responsible for the square hysteresis loop is necessary for further significant improvements in these materials. The investigation reported in this paper was undertaken to obtain magnetostriction data on a compositional series of ferrites in which there exists an important variation in the character of the hysteresis loop. A significant correlation was found between the magnetostriction and the hysteresis data. The isotropic saturation magnetostriction for these polycrystalline materials was found to change sign, going through zero at the optimum composition for hysteresis-loop squareness in this compositional series. In addition, the sign of the magnetostriction at low fields, which in nearly all cases is opposite to that at high fields, also changes at this optimum composition. These data have been analyzed, and it has been concluded that the effective domain anisotropy and the polycrystalline saturation magnetostriction are zero at the optimum composition. A possible mechanism is advanced which explains the observed data as the result of a grain-to-grain alignment of the magnetic moments due to the anisotropy of the single-crystal magnetostriction. Because it presents information of general interest this thesis report, which has had only very limited distribution, is being issued as a Division 6 Report

TRY plant trait database – enhanced coverage and open access

Plant traits - the morphological, anatomical, physiological, biochemical and phenological characteristics of plants - determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits - almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Group 63 Seminar on Magnetism, XLII

This memo is a summary of a Group 63 seminar on magnetism. Topics include evaluation of the density of energy states at the top of the Fermi distribution, and binding energies in body-centered transition metals

TRY plant trait database - enhanced coverage and open access

10.1111/gcb.14904GLOBAL CHANGE BIOLOGY261119-18