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Hysteresis Loops (hysteresi + loop)
Selected AbstractsAnisotropic Behavior of Radiopaque NiTiPt Hypotube for Biomedical ApplicationsADVANCED ENGINEERING MATERIALS, Issue 11 2009Zhicheng Lin This paper presents the first characterization of anisotropic stress,strain behavior in micron-sized specimens cut directly from hypotubes, the starting material for the manufacture of endovascular stents and other biomedical devices, of a new radiopaque alloy NiTiPt. Experimental results show that NiTiPt hypotube has very different anisotropic characteristics when compared to its NiTi counterpart including higher tensile strength and strain, higher stress,strain nonlinearity, smaller hysteresis loop, and sharper tails during loading,unloading. [source] Universal Behavior and Electric-Field-Induced Structural Transition in Rare-Earth-Substituted BiFeO3ADVANCED FUNCTIONAL MATERIALS, Issue 7 2010Daisuke Kan Abstract The discovery of a universal behavior in rare-earth (RE)-substituted perovskite BiFeO3 is reported. The structural transition from the ferroelectric rhombohedral phase to an orthorhombic phase exhibiting a double-polarization hysteresis loop and substantially enhanced electromechanical properties is found to occur independent of the RE dopant species. The structural transition can be universally achieved by controlling the average ionic radius of the A-site cation. Using calculations based on first principles, the energy landscape of BiFeO3 is explored, and it is proposed that the origin of the double hysteresis loop and the concomitant enhancement in the piezoelectric coefficient is an electric-field-induced transformation from a paraelectric orthorhombic phase to the polar rhombohedral phase. [source] Effect of hydrodynamic multiplicity on trickle bed reactor performanceAICHE JOURNAL, Issue 1 2008Werner van der Merwe Abstract Multiple hydrodynamic states in trickle bed reactors have been the subject of numerous hydrodynamic investigations. The extent of variation in the hydrodynamic parameters (like holdup and pressure drop) is large and this variation can be expected to have a significant impact on the conversion in a reaction system. This study presents reaction data for ,-methyl styrene hydrogenation in a trickle bed reactor over a range of conditions that include gas and liquid limitations. It is seen that liquid flow rate variation induced hysteresis has a large impact on the conversion. For gas-limited reactions, the upper branch of the pressure drop hysteresis loop has a higher conversion than the lower branch at the same linear fluid velocities and catalyst weight, while for liquid-limited reactions the lower branch has a higher conversion than the upper branch (the difference in productivity being up to 20%). These trends cannot be explained by differences in wetting efficiency. Instead, it is proposed that for this system the gas,liquid mass transfer rate is the limiting step in gas-limited reactions, while the liquid,solid mass transfer rate is the limiting step in liquid-limited reactions. © 2007 American Institute of Chemical Engineers AIChE J, 2008 [source] Constraint of Oxygen Fugacity During Field-Assisted Sintering: TiO2 as a Test CaseJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2008Dat V. Quach Field-assisted sintering exposes samples in a graphite die to reducing conditions. Using TiO2 as a test case, this work shows that internal redox equlibria in the sample, rather than the graphite,CO,O2 equilibrium, appear to control the oxygen fugacity. Samples sintered at 1160°C for 20 min are homogeneous in oxygen content and have an average composition of TiO1.983±0.001. The oxygen fugacity during these sintering experiments is calculated to be about 10,16 atm, which is higher than the value obtained from thermodynamic equilibrium of graphite,CO,O2 at the given temperature. The oxygen fugacity is similar to that for the quasi-two-phase region, or hysteresis loop, representing the coexistence of reduced rutile with random crystallographic shear (CS) planes and the first ordered CS phase. [source] Core loss reduction by laser scribing in grain-oriented 3% Si,Fe under different magnetizing directionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2004K. S. Ryu Abstract To reduce the core loss of grain oriented silicon steel, various metallurgical attempts have been made. The laser scribing reduces the core loss of 3% Si,Fe, because sub-domains induced by scribing produce many active domain walls which reduce the eddy current loss. The profiles of ac hysteresis loop and core loss have been measured for samples oriented parallel and perpendicular to the [001] axis in (110)[001] grains of 3% Si,Fe before and after laser scribing. The observed ac hysteresis loop profiles have been analyzed in terms of domain reorientation under field. For the parallel and perpendicular samples, the reductions of core loss are 5.7% and 30.3% by laser scribing at the magnetic induction 1.3 T and magnetizing frequency 60 Hz. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Local Hall effect in a hybrid InSb cross junctionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2004W. Y. Kim Abstract We present the local Hall effect in a hybrid Hall device incorporating a micron-scaled InSb semiconductor cross junction and a single microstructured ferromagnetic element. A clear hysteresis loop was found to appear in the output signal for the cross junction with a ferromagnetic element due to the strong perpen- dicular component of the magnetic fringe field emanating from the edge of the ferromagnet. We demon- strate that the local fringe field from the ferromagnetic element inducing a Hall voltage improves the Hall sensitivity (4.5 ,/Oe). (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Magnetotransport and magnetic properties of p -Zn1, xMnxTe:N , Carrier-induced ferromagnetismPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2004K.-T. Nam Abstract The magnetic properties of nitrogen-doped p -Zn1, xMnxTe grown by MBE were studied through the magnetotransport measurements. In a sample of p -Zn1, xMnxTe with x = 0.034 and p = 4.7 × 1019 cm,3, a hysteresis loop was observed below 2.5 K in the Hall resistance and the magnetoresistivity, which indicates the ferromagnetic transition. From the plot of (RHall/Rsheet)2 against B/(RHall/Rsheet) at several temperatures, which corresponds to the so-called Arrott plot, we can estimate the Curie temperature (Tc) of the sample as about 3 K, suggesting that this sample has the higher Tc than ever reported. We also demonstrated, by means of light irradiation, that the strength of ferromagnetic interactions can be controlled by changing the hole concentration. An increase of the ferromagnetic behaviours such as a small increase of the coercive field was observed under light irradiation. This result strongly supports that the ferromagnetic transition in Zn1, xMnxTe is the carrier-induced one. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of film thickness on the electrical and magnetic properties of Co,Fe,Al,O filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2007M. H. Phan Abstract Influence of film thickness (t) on the electrical and magnetic properties of Co,Fe,Al,O films has been systematically investigated via means of vibrating sample magnetometry (VSM), permeability spectra and magneto-optical Kerr effect (MOKE). It is found that the electrical resistivity (,) decreases as the film thickness increases; , = 412.5 µ,cm for the t = 600 nm sample decreases to , = 368.2 µ,cm for the t = 1200 nm sample. The coercive force, measured along the easy-axis direction, decreases as the film thickness increases. Interestingly, along the hard-axis magnetization direction, the magnetic hysteresis loop is reversed and the coercive force is negative for the t = 600 and 800 nm samples. However, this peculiar feature disappears as t reaches 1200 nm, which is probably attributed to the microstructural change with respect to changes of film thickness. At a frequency of 1GHz, the hard-axis effective permeability decreases from 1252 to 1000 as the film thickness increases from 600 to 1200 nm, respectively. The VSM and MOKE results reveal an increase in magnetic anisotropy in the near-surface region of the film. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A New Chiral Schiff Base with Ferroelectric PropertyCHINESE JOURNAL OF CHEMISTRY, Issue 11 2008Xiu-Zhi LI Reaction of 1,1,1,5,5,5-hexafluoropen- tane-2,4-dione with (1S,2S)-(,)-1,2-diaminocyclohexane afforded a chiral Schiff base (1Z,4Z)-2,4-bis(trifluoromethyl)-5a,6,7,8,9,9a -hexahydro-3H -benzo[b][1,4]diazepine (1). Fluorescent analysis showed its intense emission band at 488 nm when the exciting radiation was set at 437 nm. Crystallographic analysis shows that it belongs to a non-centric space group C2 with ferroelectric behavior. A typical ferroelectric feature of electric hysteresis loop was obtained, with remanent polarization (Pr) of ca. 0.01 µC/cm2 and coercive field (Ec) of 0.27 kV/cm. [source] Textural and compositional controls on modern beach and dune sands, New ZealandEARTH SURFACE PROCESSES AND LANDFORMS, Issue 3 2007J. J. Kasper-Zubillaga Abstract Textural, compositional, physical and geophysical determinations were carried out on 111 beach and dune sand samples from two areas in New Zealand: the Kapiti,Foxton coast sourced by terranes of andesite and greywackes and the Farewell Spit,Wharariki coast sourced by a wide variety of Paleozoic terranes. Our aim is to understand how long-shore drift, beach width and source rock control the sedimentological and petrographic characteristics of beach and dune sands. Furthermore, this study shows the usefulness of specific minerals (quartz, plagioclase with magnetite inclusions, monomineralic opaque grains) to interpret the physical processes (fluvial discharges, long-shore currents, winds) that distribute beach and dune sands in narrow and wide coastal plains. This was done by means of direct (grain size and modal analyses) and indirect (specific gravity, magnetic/non-magnetic separations M/NM, magnetic susceptibility measurements, hysteresis loops) methods. Results are compared with beach sands from Hawaii, Oregon, the Spanish Mediterranean, Elba Island and Southern California. Compositionally, the Kapiti,Foxton sands are similar to first-order immature sands, which retain their fluvial signature. This results from the high discharge of rivers and the narrow beaches that control the composition of the Kapiti,Foxton sands. The abundance of feldspar with magnetite inclusions controls the specific gravity of the Kapiti,Foxton sands due to their low content of opaque minerals and coarse grain size. Magnetic susceptibility of the sands is related mainly to the abundance of feldspars with Fe oxides, volcanic lithics and free-opaque minerals. The Farewell Spit,Wharariki sands are slightly more mature than the Kapiti,Foxton sands. The composition of the Farewell Spit,Wharariki sands does not reflect accurately their provenance due to the prevalence of long-shore drift, waves, little river input and a wide beach. Low abundance of feldspar with magnetite inclusions and free opaque grains produces poor correlations between specific gravity (Sg) and Fe oxide bearing minerals. The small correlation between opaque grains and M/NM may be related to grain size. The magnetic susceptibility of Farewell Spit,Wharariki sands is low due to the low content of grains with magnetite inclusions. Hysteresis and isothermal remnant magnetization (IRM) agree with the magnetic susceptibility values. Copyright © 2006 John Wiley & Sons, Ltd. [source] Cyclic tests of post-tensioned precast CFT segmental bridge columns with unbonded strandsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2006Chung-Che Chou Abstract Two ungrouted post-tensioned, precast concrete-filled tube (CFT) segmental bridge columns were tested under lateral cyclic loading to evaluate the seismic performance of the column details. The specimens included a load stub, four equal-height circular CFT segments, and a footing. Strands were placed through the column and post-tensioned to provide a precompression of the column against the footing. One specimen also contained energy-dissipating devices at the base to increase the hysteretic energy. The test results showed that (1) both specimens could develop the maximum flexural strength at the design drift and achieve 6% drift with small strength degradation and residual displacement, (2) the proposed energy-dissipating device could increase energy dissipation in the hysteresis loops, and (3) the CFT segmental columns rotated not only about the base but also about the interface above the bottom segment. This study proposed and verified a method to estimate the experimental flexural displacement using two plastic hinges in the segmental column. Copyright © 2005 John Wiley & Sons, Ltd. [source] A unified formulation of the piecewise exact method for inelastic seismic demand analysis including the P -delta effectEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 6 2003M. N. Ayd Abstract The non-linear analysis of single-degree-of-freedom (SDOF) systems provides the essential background information for both strength-based design and displacement-based evaluation/design methodologies through the development of the inelastic response spectra. The recursive solution procedure called the piecewise exact method, which is efficiently used for the response analysis of linear SDOF systems, is re-formulated in this paper in a unified format to analyse the non-linear SDOF systems with multi-linear hysteresis models. The unified formulation is also capable of handling the P-delta effect, which generally involves the negative post-yield stiffness of the hysteresis loops. The attractiveness of the method lies in the fact that it provides the exact solution when the loading time history is composed of piecewise linear segments, a condition that is perfectly satisfied for the earthquake excitation. Based on simple recursive relationships given for positive, negative and zero effective stiffnesses, the unified form of the piecewise exact method proves to be an extremely powerful and probably the best tool for the SDOF inelastic time-history and response spectrum analysis including the P-delta effect. A number of examples are presented to demonstrate the implementation of the method. Copyright © 2003 John Wiley & Sons, Ltd. [source] High-Density Periodically Ordered Magnetic Cobalt Ferrite Nanodot Arrays by Template-Assisted Pulsed Laser DepositionADVANCED FUNCTIONAL MATERIALS, Issue 21 2009Xingsen Gao Abstract A novel nanopatterning method using pulsed laser deposition through an ultrathin anodic aluminium oxide (AAO) membrane mask is proposed to synthesize well-ordered nanodot arrays of magnetic CoFe2O4 that feature a wide range of applications like sensors, drug delivery, and data storage. This technique allows the adjustment of the array dimension from ,35 to ,300,nm in diameter and ,65 to ,500,nm in inter-dot distance. The dot density can be as high as 0.21 Terabit in.,2. The microstructure of the nanodots is characterized by SEM, TEM, and XRD and their magnetic properties are confirmed by well-defined magnetic force microscopy contrasts and by hysteresis loops recorded by a superconducting quantum interference device. Moreover, the high stability of the AAO mask enables the epitaxial growth of nanodots at a temperature as high as 550,°C. The epitaxial dots demonstrate unique complex magnetic domains such as bubble and stripe domains, which are switchable by external magnetic fields. This patterning method creates opportunities for studying novel physics in oxide nanomagnets and may find applications in spintronic devices. [source] Unraveling Deterministic Mesoscopic Polarization Switching Mechanisms: Spatially Resolved Studies of a Tilt Grain Boundary in Bismuth FerriteADVANCED FUNCTIONAL MATERIALS, Issue 13 2009Brian J. Rodriguez Abstract The deterministic mesoscopic mechanism of ferroelectric domain nucleation is probed at a single atomically-defined model defect: an artificially fabricated bicrystal grain boundary (GB) in an epitaxial bismuth ferrite film. Switching spectroscopy piezoresponse force microscopy (SS-PFM) is used to map the variation of local hysteresis loops at the GB and in its immediate vicinity. It is found that the the influence of the GB on nucleation results in a slight shift of the negative nucleation bias to larger voltages. The mesoscopic mechanisms of domain nucleation in the bulk and at the GB are studied in detail using phase-field modeling, elucidating the complex mechanisms governed by the interplay between ferroelectric and ferroelastic wall energies, depolarization fields, and interface charge. The combination of phase-field modeling and SS-PFM allows quantitative analysis of the mesoscopic mechanisms for polarization switching, and hence suggests a route for unraveling the mechanisms of polarization switching at a single defect level and ultimately optimizing materials properties through microstructure engineering. [source] Interpreting sediment delivery processes using suspended sediment-discharge hysteresis patterns from nested upland catchments, south-eastern AustraliaHYDROLOGICAL PROCESSES, Issue 17 2009Hugh G. Smith Abstract In this study, suspended sediment concentration (SSC) and discharge (Q) hysteresis patterns recorded at the outlets of two nested upland catchments in south-eastern Australia were examined. Detailed monitoring of sediment flux was undertaken in a 1·64 km2 sub-catchment located within a 53·5 km2 catchment for which sediment yield was measured and the extent of incised channels mapped. The analysis of SSC,Q hysteresis patterns was supplemented by these additional datasets to contribute to the explanation of observed patterns. Clockwise SSC,Q hysteresis loops (with the suspended sediment peak leading the discharge peak) were recorded most frequently at both sites. This was attributed to initial rapid delivery of sediment from channel banks, the dominant sediment source in the sub-catchment and probably also for the catchment, in conjunction with remobilization of in-channel fine sediment deposits. Sediment exhaustion effects were considered to enhance clockwise hysteresis, with reduced SSC on the falling limb of event hydrographs. Pronounced exhaustion effects were observed on some multi-rise events, with subsequent flow peaks associated with much reduced sediment peaks. To compare SSC,Q hysteresis patterns between the two catchments, a dimensionless similarity function (SF) was derived to differentiate paired-event hysteresis patterns according to the extent of pattern similarity. This analysis, coupled with the other datasets, provided insight into the function of erosion and sediment delivery processes across the spatial scales examined and indicated the dependency of between-scale suspended sediment transfer on defined flow event scenarios. Quantitative measures of event SSC,Q hysteresis pattern similarity may provide a mechanism for linking the timing and magnitude of process response across spatial scales. This may offer useful insights into the between-scale linkage of dominant processes and the extent of downstream suspended sediment delivery. Copyright © 2009 John Wiley & Sons, Ltd. [source] Magnetically Anisotropic Cobalt and Iron Nanofibers via ElectrospinningADVANCED MATERIALS, Issue 23 2007M. Graeser Magnetically anisotropic cobalt and iron nanofibers (see figure) are obtained via oriented polymer-supported electrospinning and subsequent reduction and thermal treatment. The cobalt and iron nature of the fibers is confirmed by XRD analysis. Fibers of both metals show ferromagnetic behavior. Parallel aligned iron nanofibers revealed anisotropic hysteresis loops depending on field-fiber orientation. [source] Large Electric Polarization and Exchange Bias in Multiferroic BiFeO3,ADVANCED MATERIALS, Issue 11 2006J. Dho Low-leakage BiFeO3 films have been grown with saturated ferroelectric hysteresis loops (see figure) and a very large remanent polarization. The antiferromagnetic nature of BiFeO3 films is confirmed by the appearance of an exchange bias in BiFeO3 -based spin-valve multilayers. The results imply that there is potential for room-temperature applications of BiFeO3 that combine ferroelectric and antiferromagnetic functionality. [source] Temperature-Insensitive Large Strain of (Bi1/2Na1/2)TiO3,(Bi1/2K1/2)TiO3,(K0.5Na0.5)NbO3 Lead-Free PiezoceramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2010Klaus T. P. Seifert The effect of (K0.5Na0.5)NbO3 (KNN) addition on the ferroelectric behavior of (Bi1/2Na1/2)TiO3,(Bi1/2K1/2)TiO3 (BNT,BKT) lead-free piezoceramics was investigated. Polarization and strain hysteresis loops indicate that the ferroelectric order is disrupted significantly with the addition of KNN as a replacement for BNT and the destabilization of the ferroelectric order is accompanied by an enhancement of the unipolar strain, which peaks at a value of ,0.48% (corresponding to a large signal d33 of ,600 pm/V) at 1 mol% KNN content. This strain was analyzed as derived from an electrostrictive effect at lower electric fields and a converse piezoelectric effect at higher electric fields. By limiting the electric driving field to exclude the contribution from the converse piezoelectric effect, a temperature-insensitive large-field d33 of ,250 pm/V up to 200°C was achieved. [source] Large Piezoelectric Coefficient in Tb-Doped BiFeO3 FilmsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2010Xuemei Chen Polycrystalline BiFeO3 and Bi1,xTbxFeO3 (BTFO) (x=0.05,0.16) thin films were deposited on indium tin oxide/glass substrates via a metal organic deposition method. The influence of Tb doping content on the structure and multiferroic properties was investigated. X-ray diffraction results reveal that there may exist a structure transition around x=0.11 in the BTFO system. Well-saturated and rectangular P,E hysteresis loops can be observed in all BTFO films. The BTFOx=0.11 film exhibits the maximum values of the remanent out-of-plane piezoelectric coefficient (d33=140 pm/V) and saturated magnetization (Ms=22.2 emu/cm3). [source] Microstructure,Dielectric Properties Relationship in Ba0.6Sr0.4TiO3,Mg2SiO4,Al2O3 Composite CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2010Ying Chen 0.60Ba0.6Sr0.4TiO3(BST),(0.40,x)Mg2SiO4(MS),xAl2O3 (x=0, 0.5, 3, 5wt%) composite ceramics exhibit excellent characteristics suitable for tunable device applications. With increasing amount of Al, the dielectric peak can be quantitatively broadened and suppressed; the "phase transition temperature"Tc or (Tm) shifts to a lower temperature. Meanwhile, the tunability is still high in a wider temperature range. Far from Tc, pyroelectric effects are observed by using the Byer and Roundy technology and Slim polarization hysteresis loops are observed under high ac dielectric field at 10Hz. These proved the existence of spontaneous polarization in certain possible orientations in a broad temperature range above Tc in the paraelectric medium and reveal why 0.60BST,(0.40,x)MS,xAl2O3 have such remarkable dielectric nonlinearity. [source] Effect of La Doping on the Phase Conversion, Microstructure Change, and Electrical Properties of Bi2Fe4O9 CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2009Ju Hong Miao Undoped and La-doped Bi2Fe4O9 ceramics were synthesized using a soft chemical method. It is observed that in calcining La-doped Bi2Fe4O9, Bi(La)FeO3 phase rather than Bi2,xLaxFe4O9 gradually increases with increasing La doping content. The phase conversion from mullite-type structure of Bi2Fe4O9 to rhombohedrally distorted perovskite one of Bi(La)FeO3 with increasing La doping content indicates that La doping can stabilize the structure of BiFeO3. This is further evidenced that Bi2Fe4O9 can be directly converted to Bi(La)FeO3 by heating the mixtures of nominal composition of Bi2Fe4O9/xLa2O3. Furthermore, the microstructure changes and the room temperature hysteresis loops and leakage current for Bi2,xLaxFe4O9 with x=0 and 0.02 were characterized. [source] Preparation and Fluorescent and Magnetic Properties of Polyurethane/Eu(MA)3 FilmsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 24 2007Shuxue Zhou Abstract Europium(III) (Eu3+)-doped polyurethane films were prepared by mixing Eu-methacrylic acid complex (Eu(MA)3) with aliphatic polyurethane oligomer and subsequently curing under UV irradiation. Transmission electron microscopy photos and the appearance of the resulting hybrid films showed that phase separation occurred only at an Eu(MA)3 content above 20 wt.-%. Fluorescence spectra indicated that the fluorescence of Eu3+ was barely influenced by the polyurethane matrix and its intensity increased with an Eu(MA)3 content in the range of approximately 0 to 10 wt.-%. An obvious applied external-field-dependent magnetization (M) of polyurethane/Eu(MA)3 films, namely, an increasing M at low field and a decreasing M at high field, was observed at room temperature from the hysteresis loops, which was influenced by both the Eu(MA)3 content and the ultrasonication imposed on the coatings before curing. It seems that ultrasonication leads to a thermodynamically-unstable structure of Eu3+ in hybrid films, which can be fixed by UV curing but gradually rearranges to its original form during the thermal-curing process, and enhances the diamagnetic part of the hybrid film. Thus, the magnetic property of Eu3+ -doped polyurethane film at room temperature can be adjusted by simply changing the preparation method and the Eu(MA)3 content instead of the type of Eu3+ -organic complex. [source] Electrocaloric effect in antiferroelectric PbZrO3 thin filmsPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 5 2008Jayanta Parui Abstract Antiferroelectric PbZrO3 thin films have been deposited on Pt(111)/Ti/SiO2/Si substrate by polymer modified sol,gel route. Temperature dependent P ,E hysteresis loops have been measured at 51 MV/m within a temperature range of 40 °C to 330 °C. The maximum electrocaloric effect ,0.224 × 10,6 K mV,1 has been observed near the dielectric phase transition temperature (235 °C) of the thin films. The electrocaloric effect and its strong temperature dependence have been attributed to nearly first-order phase transition. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Piezoresponse imaging and local characterization of ferroelectric domains in Pb(Zn1/3Nb2/3)O3,7%PbTiO3 single crystalsPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 2 2007H. R. Zeng Abstract Ferroelectric domain structures of (001)-oriented Pb(Zn1/3Nb2/3)O3,7%PbTiO3 (PZN-7%PT) single crystals were visualized and characterized by piezoresponse force microscopy (PFM). Locally regular domain configurations are found to be possibly related to the stable macroscopic properties in the PZN-7%PT single crystals. Nanoscale piezoresponse hysteresis loops measured by PFM tip revealed no evidence of local domain switching behavior in the PZN-7%PT single crystal. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Linear and nonlinear magneto-optical response of ultrathin Co/Au/Mo and Co/Mo films grown on sapphire substratesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2008A. Stupakiewicz Abstract We report studies of the linear and nonlinear magneto-optical properties of epitaxial ultrathin Co films grown on sapphire substrates covered with Mo or Mo/Au buffers. Changes of the crystallographic symmetry and magnetization of buried interfaces were deduced from the magneto-optical Kerr effect hysteresis loops and magnetization-induced second-harmonic generation (MSHG). Depending on the buffer, two-fold (for Mo buffer) or six-fold (for Mo/Au buffer) symmetries were observed in both inplane magnetic anisotropy and MSHG intensity. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] FePt thin film irradiated with high energy ionsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2007M. Jaafar Abstract The changes in structural and magnetic properties of FePt thin films due to the irradiation with high energy ions (Br7+ and Cl2+) were studied. From the hysteresis loops dominating in-plane anisotropy is derived, however, the samples present a minor out-of-plane component. The structure and the magnetic properties of the films can be tuned by selecting the appropriate irradiation parameters (different ions, energies and fluencies). For the irradiation parameters used in this study an in-plane anisotropy is favoured. Irradiation with Br7+ seems to induce minor changes in the structural ordering of the thin films, whereas the Cl2+ ions promote the amorphization of the surface of the films. In addition, a magnetic thin film patterned at the micrometer scale was obtained after irradiation through a micrometric mask. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical, structural, and magnetic properties of p-type GaN implanted with Fe+ (5 and 10 at%)PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2007Yoon Shon Abstract p-type GaN epilayers were prepared by metalorganic chemical vapor deposition and subsequently implanted with Fe+. The results of energy dispersive X-ray peak displayed the Fe-injected concentration of 5 and 10 at%, respectively. The results of photoluminescence measurement show that optical transitions related to Fe appear at 2.5 and 3.1 eV. It was confirmed that the photoluminescence peak at 2.5 eV is a donor-Fe acceptor transition and the photoluminescence peak at 3.1 eV is a conduction band-Fe acceptor transition. Apparent ferromagnetic hysteresis loops measured at 10 and 300 K with the Fe concentration of 10 at% were observed, and the temperature-dependent magnetization displayed a ferromagnetic behavior persisting up to 300 K. The systematic enhancement of ferromagnetic hysteresis loops for GaN implanted with high doses of Fe (5 , 10 at%) takes place with an increase in the annealing temperature from 700 to 850 °C. The trends of magnetic properties coincide with the results of the increased full width at half maximum of triple axis diffraction for GaN (0002) including the appearance of GaFeN, the enhanced Fe-related photoluminescence transitions, and the increased sizes of symmetric spin ferromagnetic domains GaFeN in atomic force microscopy and magnetic force microscopy systematically. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Core loss depending on magnetizing angle from easy axis in grain-oriented 3% silicon-ironPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2004K. S. Ryu Abstract The profiles of ac hysteresis loops have been measured as function of the angle , between H -field and [001] axis in (110)[001] grain oriented 3% silicon-iron. As , increases, for , , 30° the loop changes into a wasp-waisted shape with inflection points. The observed ac hysteresis loop profiles have been analyzed in terms of domain reorientation under field. The core losses in silicon-iron are measured for various magnetizing angles with respect to the easy axis at magnetizing frequency 50 Hz and 60 Hz and at magnetic induction 1.3 T and 1.0 T. At magnetic induction 1.3 T, the core loss increased to near 70° and decreased at magnetizing frequency 60 Hz, but at 50 Hz this trend was different from 60 Hz and the core loss was monotonously increased. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Triple-like hysteresis loop and electric field-induced tetragonal,orthorhombic phase transition in the 0.62Pb(Mg1/3Nb2/3)O3,0.38PbTiO3 single crystalPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003Xiangyong Zhao Abstract We report an observation of triple-like P,E hysteresis loops and an electric field-induced tetragonal,orthorhombic phase transition in the 0.62Pb(Mg1/3Nb2/3)O3,0.38PbTiO3 single crystal. The stability of the induced orthorhombic phase was studied as a function of temperature and electric field, which is applied along the ,011, direction of the original tetragonal phase. [source] The influence of dipolar interaction on magnetic properties in nanomagnets with different shapesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2010Ying Li Abstract With the Monte Carlo method, we investigate the magnetic properties of four nanomagnets of different shapes, i.e., the circular-shaped, the square-shaped, the elliptical, and the ring-shaped nanomagnets. A systematic study of the effects of the dipolar interaction on the magnetic configurations is performed in these nanomagnets, and further the coercive field and the remanence as a function of dipolar interaction are analyzed. The results show that the magnetic configuration and thus the magnetization reversal process of nanomagnets are dependent strongly on the strength of dipolar interactions. For the case of small dipolar interaction, the magnetization reversal process is mainly dominated by spin rotation, while the reversal transforms to the vortex nucleation and propagation formations with increasing dipolar interaction. Moreover, if the dipolar interaction is neglected in the calculation of the total energy, no clear difference is found among hysteresis loops of four nanomagnets with same areas, but the inclusion of dipolar interaction can lead to different hysteresis loops for nanomagnets with same areas but different shapes. This indicates that the dipolar interaction is important for accounting for the shape effect of the magnetic properties in nanomagnets. [source] | |||||||||||||||||||