Far-infrared magnetotransmission of YBa2(ZnxCu(1-x))3O(7-d)

Measurements of the far infrared magnetotransmission of YBa2(ZnxCu(1-x))3O(7-d) thin film (x = 0.025) deposited on a wedged MgO substrate are reported. The application of magnetic field perpendicular to the ab plane produces at low temperature a linear increase of transmission for frequencies below 30 cm-1. We present a model of high frequency vortex dynamics which qualitatively explains these results.Comment: 2 pages with 2 figures, presented on LT2

Magnetism and Electronic Structure in ZnFe2_2O4_4 and MnFe2_2O4_4

Density functional calculations are used to study magnetic and electronic properties of the spinel ferrites, ZnFe$_2$O$_4$ and MnFe$_2$O$_4$. Correct magnetic orderings are obtained. ZnFe$_2$O$_4$ is predicted to be a small gap insulator in agreement with experiment. MnFe$_2$O$_4$ is found to be a low carrier density half-metal in the fully ordered state. However, strong effects on the electronic structure are found upon partial interchange of Fe and Mn atoms. This indicates that the insulating character may be due to Anderson localization associated with the intersite Mn-Fe disorder.Comment: 3 pages, submitted to mmm01 conferenc

Spin canting across core/shell Fe3O4/MnxFe3−xO4 nanoparticles

Magnetic nanoparticles (MNPs) have become increasingly important in biomedical applications like magnetic imaging and hyperthermia based cancer treatment. Understanding their magnetic spin configurations is important for optimizing these applications. The measured magnetization of MNPs can be significantly lower than bulk counterparts, often due to canted spins. This has previously been presumed to be a surface effect, where reduced exchange allows spins closest to the nanoparticle surface to deviate locally from collinear structures. We demonstrate that intraparticle effects can induce spin canting throughout a MNP via the Dzyaloshinskii-Moriya interaction (DMI). We study ~7.4 nm diameter, core/shell Fe3O4/MnxFe3−xO4 MNPs with a 0.5 nm Mn-ferrite shell. Mössbauer spectroscopy, x-ray absorption spectroscopy and x-ray magnetic circular dichroism are used to determine chemical structure of core and shell. Polarized small angle neutron scattering shows parallel and perpendicular magnetic correlations, suggesting multiparticle coherent spin canting in an applied field. Atomistic simulations reveal the underlying mechanism of the observed spin canting. These show that strong DMI can lead to magnetic frustration within the shell and cause canting of the net particle moment. These results illuminate how core/shell nanoparticle systems can be engineered for spin canting across the whole of the particle, rather than solely at the surface

Multiple-Dwell Serial-Search Code Acquisition of Spread-Spectrum Receiver - Mean Acquisition Time at Fixed False-Alarm Penalty

The contribution summarizes the results of the mean code acquisition time calculations of multiple - dwell serial search detector with fixed false-alarm penalty. The repeated calculations enable to choose optimum values of the synchronizer parameters

Multiple-Dwell Serial-Search Code Acquisition of Spread-Spectrum Receiver - Mean Acquisition Time at Fixed False-Alarm Penalty

The contribution summarizes the results of the mean code acquisition time calculations of multiple - dwell serial search detector with fixed false-alarm penalty. The repeated calculations enable to choose optimum values of the synchronizer parameters

Distributed Partial Order Reduction of State Spaces

State space explosion is a fundamental obstacle in formal verification of concurrent systems. Several techniques for combating this problem have emerged in the past few years, among which the two we are interested in are: partial order reduction and distributed memory state exploration. While the first one tries to reduce the problem to a smaller one, the other one tries to extend the computational power to solve the same problem. In this paper, we consider a combination of these two approaches and propose a distributed memory algorithm for partial order reduction