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Field Range (field + range)
Selected AbstractsGiant Electric Field Tuning of Magnetic Properties in Multiferroic Ferrite/Ferroelectric HeterostructuresADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Ming Liu Abstract Multiferroic heterostructures of Fe3O4/PZT (lead zirconium titanate), Fe3O4/PMN-PT (lead magnesium niobate-lead titanate) and Fe3O4/PZN-PT (lead zinc niobate-lead titanate) are prepared by spin-spray depositing Fe3O4 ferrite film on ferroelectric PZT, PMN-PT and PZN-PT substrates at a low temperature of 90,°C. Strong magnetoelectric coupling (ME) and giant microwave tunability are demonstrated by a electrostatic field induced magnetic anisotropic field change in these heterostructures. A high electrostatically tunable ferromagnetic resonance (FMR) field shift up to 600,Oe, corresponding to a large microwave ME coefficient of 67,Oe cm kV,1, is observed in Fe3O4/PMN-PT heterostructures. A record-high electrostatically tunable FMR field range of 860 Oe with a linewidth of 330,380,Oe is demonstrated in Fe3O4/PZN-PT heterostructure, corresponding to a ME coefficient of 108,Oe cm kV,1. Static ME interaction is also investigated and a maximum electric field induced squareness ratio change of 40% is observed in Fe3O4/PZN-PT. In addition, a new concept that the external magnetic orientation and the electric field cooperate to determine microwave magnetic tunability is brought forth to significantly enhance the microwave tunable range up to 1000,Oe. These low temperature synthesized multiferroic heterostructures exhibiting giant electrostatically induced tunable magnetic resonance field at microwave frequencies provide great opportunities for electrostatically tunable microwave multiferroic devices. [source] Strength Properties of Poled Lead Zirconate Titanate Subjected to Biaxial Flexural Loading in High Electric FieldJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2010Hong Wang The mechanical strength of poled lead zirconate titanate (PZT) has been studied using ball-on-ring (BoR) biaxial flexure tests with a high electric field applied concurrently. Both the as-received and the aged PZT specimens were tested. The Weibull plot and a 95% confidence ratio ring were used to characterize the responses of mechanical strength under various electric loading conditions. A fractographical study has been conducted at the same time, and the fracture origins or strength-limiting flaws of tested PZT specimens have been identified and characterized accordingly. The fracture toughness was further estimated to correlate with the obtained fracture stresses and flaws. It has been observed that electric field affects the mechanical strength of poled PZT, and the degree of the effect depends on the sign and magnitude of the applied electric field. Within the examined electric field range of ,3 to +3 times the coercive field, an increasing electric field resulted in a rapid strength decrease and a sharp increase with the turning point around the negative coercive field. Surface-located volume-distributed flaws were identified to be strength limiting for this PZT material. Variations of the mechanical strength with the electric field were believed to be related to the domain switching and amount of switchable domains. An aging effect on the mechanical strength of poled PZT could be significant, especially in the OC condition. These results and observations have the potential to serve probabilistic reliability analysis and design optimization of multilayer PZT piezo actuators. [source] Exciton states and tunneling in semimagnetic asymmetric double quantum wellsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2010S. V. Zaitsev Abstract Exciton level structure and interwell relaxation are studied in Cd(Mn,Mg)Te-based asymmetric double quantum wells (ADQWs) by a steady-state optical spectroscopy in magnetic fields up to B,=,10,T. The as grown heterostructures with CdTe QWs and nonmagnetic interwell CdMgTe barrier were subjected to a rapid temperature annealing to introduce Mn and Mg atoms from opposite barriers inside the QWs which results in a formation of the ADQW with completely different magnetic field behavior of the intrawell excitons. The giant Zeeman effect in the QW with magnetic Mn ions gives rise to a crossing of the ground exciton levels in two QWs at BC,,,3,6,T which is accompanied by a reverse of the interwell tunneling direction. In a single-particle picture the exciton tunneling is forbidden at B,<,1,T as supported by calculations. Experimentally, nevertheless, a very efficient interwell relaxation of excitons is found at resonant excitation in the whole magnetic field range, regardless of the tunneling direction, emphasizing importance of excitonic correlations in the interwell tunneling. At nonresonant excitation an unexpectedly slow relaxation of the ,, -polarized excitons from the nonmagnetic QW to the ,+ -polarized ground state in the semimagnetic QW is observed at B,>,BC, giving rise to a nonequilibrium distribution of excitons in ADQW. A strong dependence of the total circular polarization degree on the hh,lh splitting ,hh,lh in the nonmagnetic QW is found and attributed to the spin dependent interwell tunneling controlled by an exciton spin relaxation. Different charge-transfer mechanisms are analyzed in details and an elastic scattering due to a strong disorder is suggested as the main tunneling mechanism with the underlying influence of the valence band-mixing. [source] Generalized theoretical approach to quasi-one-dimensional molecular magnetsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2006R. Pe Abstract Two quasi-one-dimensional compounds [LnIII(terpy)(DMF)4][WV(CN)8] · 6H2O, where Ln stands for Gd or Sm, were synthesized and the measurements of their magnetic features were carried out. Magnetization was measured at 2K in the field range 0,5 T. To extract physical information from the experimental data a generalization of the theoretical approach given by Verdaguer et al. (Phys. Rev. B 29 , 5144 (1984)) [1] is put forward. That theoretical model is found to fit the data well. It allows for the determination not only of the coupling constant but also of the zero-field splitting parameter. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Apparent biological effect of strong magnetic field on mosquito egg hatchingBIOELECTROMAGNETICS, Issue 2 2004Hongjun Pan Abstract Apparent biological effects of strong magnetic fields were observed in the hatching behavior of fresh mosquito eggs in the center of 9.4 and 14.1 T magnets. In the first experiment performed at 20,±,1 °C, the hatching was delayed 32 h by a 9.4 T magnetic field and 71 h by a 14.1 T magnetic field. In the second experiment performed at 22,±,1 °C, the hatching was delayed 14 h by a 9.4 T magnetic field and 27 h by a 14.1 T magnetic field. In the magnetic field range of this study, the hatching delay increases nonlinearly with the intensity of the magnetic field. The experimental results also suggest that the biological effects of magnetic fields could be reversible or partially reversible to some extent. Bioelectromagnetics 25:84,91, 2004. © 2004 Wiley-Liss, Inc. [source] The pure parsimony haplotyping problem: overview and computational advancesINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 5 2009Daniele Catanzaro Abstract Haplotyping estimation from aligned single-nucleotide polymorphism fragments has attracted more and more attention in recent years due to its importance in analysis of many fine-scale genetic data. Its application fields range from mapping of complex disease genes to inferring population histories, passing through designing drugs, functional genomics, and pharmacogenetics. The literature proposes a number of estimation criteria to select a set of haplotypes among possible alternatives. Usually, such criteria can be expressed under the form of objective functions, and the sets of haplotypes that optimize them are referred to as optimal. One of the most important estimation criteria is the pure parsimony, which states that the optimal set of haplotypes for a given set of genotypes is that having minimal cardinality. Finding the minimal number of haplotypes necessary to explain a given set of genotypes involves solving an optimization problem, called the pure parsimony haplotyping (PPH) estimation problem, which is notoriously -hard. This article provides an overview of PPH, and discusses the different approaches to solution that occur in the literature. [source] | |||||||||||||