bluuebunny/crossref_metadata_2025 huggingface dataset:
Twentieth century tropical sea surface temperature trends revisited
Authors: Deser Clara , Phillips Adam S. , Alexander Michael A.
Published: May 2010

This study compares the global distribution of 20th century SST and marine air temperature trends from a wide variety of data sets including un‐interpolated archives as well as globally‐complete reconstructions. Apart from the eastern equatorial Pacific, all datasets show consistency in their statistically significant trends, with warming everywhere except the far northwestern Atlantic; the largest warming trends are found in the middle latitudes of both hemispheres. Two of the SST reconstructions exhibit statistically significant cooling trends over the eastern equatorial Pacific, in disagreement with the un‐interpolated SST and marine air temperature datasets which show statistically significant warming in this region. Twentieth century trends in tropical marine cloudiness, precipitation and SLP from independent data sets provide physically consistent evidence for a reduction in the strength of the atmospheric Walker Circulation accompanied by an eastward shift of deep convection from the western to the central equatorial Pacific.
Post Market Monitoring of GM Herbicide-Tolerant Crops
Authors: Dewar Alan
Published: May 2010

As soon as humans adopted agriculture as the principle means of feeding themselves, they have had an effect on the environment, and by implication, also on biodiversity. It is not possible to grow crops in an intensive manner without doing so, but it is necessary to do so to feed the population. In this respect, the use of herbicides or other weed control practices (e.g. hand-hoeing) inevitably will have an effect on biodiversity, whether those methods are used in conventional, organic or genetically modified herbicide-tolerant (GMHT) crops. Recent literature from the UK following the Farm Scale Evaluations (FSE) of the environmental impact of GMHT oilseed rape, maize and sugar beet suggests that the recommended weed management techniques applied in the cultivation of GMHT crops caused indirect effects on non-target organisms by affecting the biodiversity of plants within a field and the creatures which depend on them. Reductions in the number of weeds in glufosinate-treated HT-oilseed rape, and glyphosate-treated HTsugar beet compared to conventionally managed crops resulted in significant reductions in weed biomass (as might be expected from a superior treatment) and subsequent weed seed production later in the season and in following crops. In contrast, weed biomass and seeds were increased in glufosinate-treated HT-maize crops, leading to higher numbers of some invertebrates that fed on or were associated with the greater mass of decaying plant matter present. These effects were entirely related to the efficacy of weed control by the different herbicide regimes, and were not a feature of the HT crops themselves. They would occur with any herbicide/crop combination that changed the spectrum and density of weeds present. A much greater effect on biodiversity was seen between crops than between herbicide regimes, with non-GM maize having the greatest adverse effect on biodiversity compared to oilseed rape and sugar beet. Thus it is the growing of crops in the first place that is likely to have the greatest impact on the environment not whether it is GM or not. In this context, how is it possible to devise methods of post-market monitoring of GMHT crops? What should be the baseline against which environmental impact is measured? How can this be done simply without incurring the huge costs of studies such as the FSE in the UK? This presentation will present a personal view of the FSE and other research results that could provide guidelines for future introductions of GMHT crops in Europe.
Experienced Speech-Language Pathologists' Responses to Ethical Dilemmas: An Integrated Approach to Ethical Reasoning
Authors: Kenny Belinda , Lincoln Michelle , Balandin Susan
Published: May 2010

Purpose

To investigate the approaches of experienced speech-language pathologists (SLPs) to ethical reasoning and the processes they use to resolve ethical dilemmas.

Method

Ten experienced SLPs participated in in-depth interviews. A narrative approach was used to guide participants' descriptions of how they resolved ethical dilemmas. Individual narrative transcriptions were analyzed by using the participant’s words to develop an ethical story that described and interpreted their responses to dilemmas. Key concepts from individual stories were then coded into group themes to reflect participants' reasoning processes.

Results

Five major themes reflected participants' approaches to ethical reasoning: (a) focusing on the well-being of the client, (b) fulfilling professional roles and responsibilities, (c) attending to professional relationships, (d) managing resources, and (e) integrating personal and professional values. SLPs demonstrated a range of ethical reasoning processes: applying bioethical principles, casuistry, and narrative reasoning when managing ethical dilemmas in the workplace.

Conclusions

The results indicate that experienced SLPs adopted an integrated approach to ethical reasoning. They supported clients' rights to make health care choices. Bioethical principles, casuistry, and narrative reasoning provided useful frameworks for facilitating health professionals' application of codes of ethics to complex professional practice issues.
Properties of the Narrative Scoring Scheme Using Narrative Retells in Young School-Age Children
Authors: Heilmann John , Miller Jon F. , Nockerts Ann , Dunaway Claudia
Published: May 2010

Purpose

To evaluate the clinical utility of the narrative scoring scheme (NSS) as an index of narrative macrostructure for young school-age children.

Method

Oral retells of a wordless picture book were elicited from 129 typically developing children, ages 5–7. A series of correlations and hierarchical regression equations were completed using microstructural measures of vocabulary and grammar to predict NSS scores.

Results

While the NSS was significantly correlated with age and each of the microstructural measures, the hierarchical regression analyses revealed a unique relationship between vocabulary and narrative macrostructure.

Conclusion

The NSS is an efficient and informative tool for documenting children’s development of narrative macrostructure. The relationship between the NSS and microstructural measures demonstrates that it is a robust measure of children’s overall oral narrative competence and a powerful tool for clinicians and researchers. The unique relationship between lexical diversity and the NSS confirmed that a special relationship exists between vocabulary and narrative organization skills in young school-age children.
Relationships Between Early Gestures and Later Language in Children With Fragile X Syndrome
Authors: Flenthrope Jennifer L. , Brady Nancy C.
Published: May 2010

Purpose

The authors hypothesized that significant positive relationships would exist between early gesture use and later language attainments in children with fragile X syndrome (FXS), as has been reported in studies with other populations.

Method

Participants were young children with FXS and limited expressive language (21 boys, 4 girls), divided into 2 subgroups based on the Childhood Autism Rating Scale (CARS; Schopler, Reichler, & Renner, 1988) scores. Data were collected when participants were about 2 years of age and again when they were about 5 years of age. Communication was assessed through the analysis of video samples obtained in the children’s homes for both observation periods. Correlational analyses were completed between early prelinguistic communication and later verbal communication scores for all participants and for children with high (>30) versus low (<30) scores on the CARS.

Results

Although no significant relationships were found between prelinguistic gesture use and language outcomes for the group of children as a whole, significant negative correlations were found for the group of children who had high CARS scores.

Conclusions

These outcomes did not support the authors' initial hypotheses. It was concluded that extensive use of developmentally early gestures by children with FXS who also have many symptoms of autism may not be a positive indicator of later language.
Effects of Parent Instruction on the Symbolic Communication of Children Using Augmentative and Alternative Communication During Storybook Reading
Authors: Kent-Walsh Jennifer , Binger Cathy , Hasham Zishan
Published: May 2010

Purpose

This study investigated the effects of a communication partner instruction strategy for parents of children using augmentative and alternative communication (AAC) on the communicative turn taking of their children. Instruction was provided within storybook-reading contexts.

Method

Two single-subject multiple-probe-across-participants designs were used to evaluate the effects of parent instruction on (a) 3 European American parents and (b) 3 African American parents. Changes in turn-taking rates and the expression of different semantic concepts in children using AAC were assessed in storybook-reading activities.

Results

All 6 parents learned to implement the communication partner interaction strategy accurately. All 6 children who used AAC increased their communicative turn taking and their language use as reflected by different semantic concepts expressed.

Conclusions

Results provide evidence that the communication partner instruction program applied within storybook-reading contexts holds significant promise in improving parent–child interaction patterns and facilitating communicative expression and turn taking in children who use AAC.
Growth of Bi doped cadmium zinc telluride single crystals by Bridgman oscillation method and its structural, optical, and electrical analyses
Authors: Carcelén V. , Hidalgo P. , Rodríguez-Fernández J. , Dieguez E.
Published: May 2010

The II-VI compound semiconductor cadmium zinc telluride (CZT) is very useful for room temperature radiation detection applications. In the present research, we have successfully grown Bi doped CZT single crystals with two different zinc concentrations (8 and 14 at. %) by the Bridgman oscillation method, in which one experiment has been carried out with a platinum (Pt) tube as the ampoule support. Pt also acts as a cold finger and reduces the growth velocity and enhances crystalline perfection. The grown single crystals have been studied with different analysis methods. The stoichiometry was confirmed by energy dispersive by x-ray and inductively coupled plasma mass spectroscopy analyses and it was found there is no incorporation of impurities in the grown crystal. The presence of Cd and Te vacancies was determined by cathodoluminescence studies. Electrical properties were assessed by I-V analysis and indicated higher resistive value (8.53×108 Ω cm) for the crystal grown with higher zinc concentration (with Cd excess) compare to the other (3.71×105 Ω cm).
First-principle investigation of 3d transition metal elements in γ′-Co3(Al,W)
Authors: Chen Min , Wang Chong-Yu
Published: May 2010

The alloying effect of 3d transition metal elements on the lattice constants and their site preferences in γ′-Co3(Al,W) are systematically studied based on a supercell model. The lattice constant of the γ′ phase is modified by the addition of 3d transition metal elements, and it increases in the order of Fe<Ni<Mn<Cr<V<Ti. Four types of site preference are identified for these 3d elements in γ′ phase by analyzing the binding energy and the impurity formation energy. Ni, Fe, V, and Ti are recognized to stabilize the γ′ phase. Their distinct alloying effect is further revealed by investigating the impurity-induced charge density difference and the partial density of states. These results are in agreement with the experimental data ever reported.
Comparative electron spin resonance study of epi-Lu2O3/(111)Si and a-Lu2O3/(100)Si interfaces: Misfit point defects
Authors: Somers P. , Stesmans A. , Afanas’ev V. V. , Tian W. , Edge L. F. , Schlom D. G.
Published: May 2010

An electron spin resonance study has been carried out on heteroepitaxial Si/insulator structures obtained through growth of epi-Lu2O3 films on (111)Si (∼4.5% mismatch) by molecular-beam epitaxy, with special attention to the inherent quality as well as the thermal stability of interfaces, monitored through occurring paramagnetic point defects. This indicates the presence, in the as-grown state, of Pb defects (∼5×1011 cm−2) with the unpaired sp3 Si dangling bond along the [111] interface normal, the archetypical defect (trap) of the standard thermal (111)Si/SiO2 interface, directly revealing, and identified as the result of, imperfect epitaxy. The occurrence of Pb defects, a major system of electrically detrimental interface traps, is ascribed to lattice mismatch with related introduction of misfit dislocations. This interface nature appears to persist for annealing in vacuum up to a temperature Tan∼420 °C. Yet, in the range Tan∼420–550 °C, the interface starts to “degrade” to standard Si/SiO2 properties, as indicated by the gradually increasing Pb density and attendant appearance of the EX center, an SiO2-associated defect. At Tan∼700 °C, [Pb] has increased to about 1.3 times the value for standard thermal (111)Si/SiO2, to remain constant up to Tan∼1000 °C, indicative of an unaltered interface structure. Annealing at Tan>1000 °C results in disintegration altogether of the Si/SiO2-type interface. Passivation anneal in H2 (405 °C) alarmingly fails to deactivate the Pb system to the device grade (sub) 1010 cm−2 eV−1 level, which would disfavor c-Lu2O3 as a suitable future high-κ replacement for the a-SiO2 gate dielectric. Comparison of the thermal stability of the c-Lu2O3/(111)Si interface with that of molecular-beam deposited amorphous-Lu2O3/(100)Si shows the former to be superior, yet unlikely to meet technological thermal budget requirements. No Lu2O3-specific point defects could be observed.
Giant magnetoimpedance effect in nanocrystalline ribbons for sensitive magnetic sensors
Authors: Dwevedi Sandhya , Markandeyulu G.
Published: May 2010

A systematic investigation of the influence of Al and V on the magnetoimpedance (MI) effect in melt-spun Fe73.5Si13⋅5B8CuNb(3−x)VxAl (x=0, 1, 1.5, and 3) ribbons has been performed in the frequency range 500 kHz–13 MHz and under dc magnetic field (Hdc) up to 60 Oe. MI was measured using impedance analyzer employing contact and noncontact methods. MIs of 61% (contact method) and 104% (noncontact method) were observed for the x=1.0 ribbon. Transverse and in-plane anisotropies were studied from the MI measurements and ferromagnetic resonance. Magnetic domain structure was studied in the ribbons through magnetic force microscopy. When the ribbon was rotated by 90° from the east-west direction, a 37% change in the MI was observed due to the earth’s magnetic field.
Microwave absorbing properties of La0.7Sr0.3MnO3 composites with negative magnetic susceptibility
Authors: Yang R. B. , Tsay C. Y. , Liang W. F. , Lin C. K.
Published: May 2010

The complex permittivity and permeability of La0.7Sr0.3MnO3 (LSMO)-epoxy composite absorbers are investigated in the microwave ranges from 2 to 18 GHz by transmission/reflection method. A negative magnetic susceptibility of perovskite oxides has been obtained in the frequency range of 4–18 GHz. By the use of the cavity perturbation technique, the negative magnetic susceptibility for 7.5–14 GHz is reconfirmed. For LSMO-epoxy composite with 80 wt % fillers, the maximum reflection loss can reach 23 dB at 10.5 GHz and the absorbing bandwidth above 10 dB is 1.5 GHz with 2 mm thickness.
Synthesis of copper ferrite from thermolysis of copper ferrimalonate precursor (invited)
Authors: Singh Jashanpreet , Kaur Harpreet , Kaur Manpreet , Randhawa B. S.
Published: May 2010

The thermolysis of copper ferrimalonate Cu3[Fe(CH2C2O4)3]2⋅9H2O has been investigated up to 1073 K in flowing air atmosphere employing various physico-chemical techniques, i.e., simultaneous TG-DTG-DSC, XRD, Mössbauer, IR, and TEM. The precursor undergoes dehydration and decomposition simultaneously to yield copper malonate and iron(II) malonate intermediates at 433 K. At higher temperature (548 K) these intermediate species decompose to CuO and α-Fe2O3, respectively. Finally, copper ferrite, CuFe2O4, has been obtained as a result of solid state reaction between α-Fe2O3 and CuO at a temperature (623 K) much lower than that for conventional ceramic method. The TEM analysis of the final thermolysis product reveals the formation of monodisperse copper ferrite nanoparticles with an average particle size of 33 nm. Magnetic studies show that these nanoparticles exhibit saturation magnetization of 2783 G and Curie temperature of 709 K. Lower magnitude of these parameters as compared with the bulk values may be attributed to the ultrafine grain size of the ferrite particles.
Synthesis of nanocrystalline Ni–Zn ferrites by combustion method with no postannealing route
Authors: Fu Chao-Ming , Syue Ming-Ru , Wei Fu-Jin , Cheng Chao-Wen , Chou Chan-Shin
Published: May 2010

Nanocrystalline Ni–Zn ferrites were synthesized by a novel combustion route without post annealing process. The sintered ferrites characterized by X-ray diffraction have shown highly pure nanocrystalline phase. Calculated by the Scherrer’s formula, the estimated crystallite size is about 26–41 nm and lattice constant of the cubic spinel was 8.353–8.458 Å. The saturated magnetization is in the range of 6–57 emu/g and the corresponded coercivity varies from 26 to 221 Oe. Further, the high frequency electromagnetic properties were investigated by analysis of magnetoimpedance spectra. The novel combustion synthesis without post annealing has implied for practical industrial fabrication of ferrites for electromagnetic applications, inherently interest of energy efficiency and cost effective.
High field-sensitivity planar Hall sensor based on NiFe/Cu/IrMn trilayer structure
Authors: Hung Tran Quang , Oh Sunjong , Sinha Brajalal , Jeong Jong-Ryul , Kim Dong-Young , Kim CheolGi
Published: May 2010

A trilayer structure, which has weak exchange coupling and high active current, has been optimized emphasizing for high field-sensitivity planar Hall effect (PHE) sensor. To illustrate the high field sensitivity of the PHE sensor, three different structures are fabricated: a bilayer thin film Ta(3)/NiFe(10)/IrMn(10)/Ta(3) (nm), a spin-valve thin film Ta(3)/NiFe(10)/Cu(1.2)/NiFe(2)/IrMn(10)/Ta(3) (nm), and a trilayer thin film Ta(3)/NiFe(10)/Cu(0.12)/IrMn(10)/Ta(3) (nm). The characterized results reveal that the field sensitivity of PHE sensor based on trilayer thin film is about one order larger than that of bilayer and is about twice larger than that of spin-valve thin film. Moreover, in trilayer structure, the thinner spacer layer gives the better performance. When the nominal thickness of spacer Cu layer is the smallest, the PHE sensor exhibits the best performance, i.e., in this experiment, it is about 0.12 nm.
The effects of geometry on magnetic response of elliptical PHE sensors
Authors: Genish Isaschar , Shperber Yishai , Naftalis Netanel , Salitra Gregory , Aurbach Doron , Klein Lior
Published: May 2010

We present planar Hall effect measurements of elliptical permalloy sensors having different aspect ratios and thicknesses along with extensive numerical simulations and analytical analysis. We identify an upper limit for the sensor minor axis on the order of 1 μm above which hysteresis effects intensify. We also find that the increased ratio between the ellipse axes and thickness enhances the magnetic response of the sensor.
The role of cations distribution on magnetic and reflection loss properties of ferrimagnetic SrFe12−x(Sn0.5Zn0.5)xO19
Authors: Ghasemi Ali , Šepelák Vladimir , Liu Xiaoxi , Morisako Akimitsu
Published: May 2010

The site preference and magnetic properties of Zn–Sn substituted strontium ferrite SrFe12−x(Sn0.5Zn0.5)xO19 particles with x=0–5 were studied using both F57e and S119n Mössbauer spectroscopies and magnetic measurements. The results show that the magnetization and magnetocrystalline anisotropy are closely related to the distributions of Zn–Sn ions on the five inequivalent crystal sites provided by the hexagonal structure of the ferrite. Mössbauer spectra show that the Zn–Sn ions preferentially occupy the 2b and 4f2 sites. The preference for these sites is responsible for the anomalous increase in the magnetization at low Zn–Sn substitutions. Based on microwave measurements of reflectivity, SrFe12−x(Sn0.5Zn0.5)xO19 is a good candidate for electromagnetic compatibility and other practical applications at high frequencies.
Temperature-dependent magnetic circular dichroism study of ferromagnetic double perovskite La2MnNiO6
Authors: Kang J.-S. , Lee S. M. , Kim D. H. , Kolesnik S. , Dabrowski B. , Park B.-G. , Kim J.-Y. , Lee Jieun , Kim Bongjae , Min B. I.
Published: May 2010

The temperature-dependent electronic structure of ferromagnetic double perovskite La2MnNiO6 has been investigated by employing soft x-ray magnetic circular dichroism (XMCD) and soft x-ray absorption spectroscopy (XAS). The measured 2p XAS spectra for Mn and Ni ions at low temperature show that most of Mn ions are formally tetravalent (3d3) and that Ni ions are divalent (3d8). The measured Ni 2p core-level x-ray photoemission spectroscopy spectrum also supports the divalent states of Ni ions. With increasing temperature, the measured XMCD intensity decreases, in agreement with its high Curie temperature. The line shapes of both XMCD and XAS spectra do not change with temperature, suggesting that the valence states of La2MnNiO6 do not change with temperature.
Effects of C and Cr contents on the magnetic properties and microstructure of directly quenched NdFeTiZrCrBC bulk magnets
Authors: Chang H. W. , Gan J. Y. , Hsieh C. C. , Zhao X. G. , Chang W. C.
Published: May 2010

Magnetic properties and microstructure of directly quenched Nd9.5Fe72.5−yTi2.5Zr0.5CryB15−xCx (x=0–1; y=0–3) magnets with a diameter of 1.1 mm and a length of 15 mm have been investigated. The thermomagnetic analysis show that the bulk magnets with x≦0.5 and y=0–3 mainly consist of magnetically hard 2:14:1 phase. Besides, a slight substitution of C for B and Cr for Fe in Nd9.5Fe72.5Ti2.5Zr0.5B15 can effectively refine the grain size of the bulk magnet with larger diameter, resulting in the remarkable enhancement of the magnetic properties. The optimal magnetic properties of Br=5.9 kG, Hic=8.2 kOe, and (BH)max=7.2 MGOe could be attained in Nd9.5Fe71.5Ti2.5Zr0.5Cr1B14.5C0.5 magnet.
Magnetic anisotropy determination and magnetic hyperthermia properties of small Fe nanoparticles in the superparamagnetic regime
Authors: Mehdaoui B. , Meffre A. , Lacroix L.-M. , Carrey J. , Lachaize S. , Respaud M. , Gougeon M. , Chaudret B.
Published: May 2010

We report on the magnetic and hyperthermia properties of 5.5 nm in diameter iron nanoparticles synthesized by organometallic chemistry, which display the bulk magnetization. Quantitative analysis of alternative susceptibility measurements allows the determination of the effective anisotropy Keff=1.3×105 J m−3. Hyperthermia measurements are performed at a magnetic field up to 66 mT and at frequencies in the range of 5–300 kHz. Maximum measured specific absorption rate (SAR) is 280 W/g. SAR displays a square dependence with the magnetic field below 30 mT but deviates from this power law at higher value. SAR is linear with the applied frequency for μ0H=19 mT. These results are discussed in the light of linear response theory.
Size dependent magnetic moments and electric polarizabilities of free Tb, Ho, and Tm clusters
Authors: Bowlan J. , van Dijk C. N. , Kirilyuk A. , Liang A. , Yin S. , Rasing Th. , de Heer W. A.
Published: May 2010

Stern–Gerlach deflection measurements have been performed on rare earth clusters TbN, HoN, and TmN (N≤40) at cryogenic temperatures (T≤77 K). TbN and HoN share a common size dependence in their magnetic moments. They both exhibit common “magic number” sizes which show reduced net magnetic moments, similar to previous observations for Gd and Dy clusters. TmN have smaller magnetic moments that do not differ significantly between cluster sizes. The reduced net magnetic moments are evidence that the atomic moments are canceled by a canted or antiferromagnetic alignment. Electric deflection experiments reveal that TmN have electric dipole moments and show an enhanced response to an electric field compared to TbN and HoN.
Magnetoresistive effects in Co/Pd multilayers on self-assembled nanoparticles (invited)
Authors: Kimling née Moser Judith , Kunej Vojko , Pernau Hans-Fridtjof , Scheer Elke , Albrecht Manfred
Published: May 2010

The deposition of Co/Pd multilayers onto self-assembled spherical particles provides a system with unique magnetic properties. The magnetic caps have high perpendicular magnetic anisotropy, are single-domain, and strongly exchange decoupled, but in electrical contact with each other, thus enabling magnetotransport measurements. By applying an external magnetic field, the caps can be switched individually. We systematically studied the magnetoresistance on a two-dimensional cap array consisting of Co/Pd multilayers deposited on particles with a diameter of 200 nm. In the vicinity of the coercive field, a hysteretic resistance peak occurs. It can be explained with the random magnetization configuration of the magnetic caps leading to an increased spin-dependent scattering of the conduction electrons. The underlying mechanism might be comparable to the one causing giant magnetoresistance in granular alloys. For temperatures above 77 K, additional resistivity contributions with high saturation fields are observed, which are tentatively explained by the decreasing size of magnetically ordered parts of the caps with increasing temperature, resulting finally in superparamagnetic behavior in the contact area between neighboring caps.
Quantitative analysis of atomic disorders in full-Heusler Co2FeSi alloy thin films using x-ray diffraction with Co Kα and Cu Kα sources
Authors: Takamura Yota , Nakane Ryosho , Sugahara Satoshi
Published: May 2010

The authors developed a new analysis technique for atomic disorder structures in full-Heusler alloys using x-ray diffraction (XRD) with Co Kα and Cu Kα sources. The technique can quantitatively evaluate all the atomic disorders for the exchanges between X, Y, and Z atoms in full-Heusler X2YZ alloys. In particular, the technique can treat the DO3 disorder that cannot be analyzed by ordinary Cu Kα XRD. By applying this technique to full-Heusler Co2FeSi alloy thin films formed by rapid thermal annealing (RTA), RTA-temperature (TA) dependence of the atomic disorders was revealed. The site occupancies of Co, Fe, and Si atoms on their original sites were 98%, 90%, and 93%, respectively, for the film formed at TA=800 °C, indicating that the RTA-formed Co2FeSi film had the L21 structure with the extremely high degree of ordering.
Thickness dependence of the molecular magnetic moment of single crystal Fe3O4 films on GaAs (100)
Authors: Zhai Y. , Sun L. , Huang Z. C. , Lu Y. X. , Li G. D. , Li Q. , Xu Y. B. , Wu J. , Zhai H. R.
Published: May 2010

The hysteresis loops and the saturation magnetization of the epitaxial Fe3O4 ultrathin films with different thicknesses grown on the GaAs (100) surface have been studied. The molecular magnetic moment of the ultrathin films was obtained from the data of the measured saturation magnetic moment of the films and the number of Fe ions in each film calculated from the measured thickness of Fe films before oxidation and film area. It was found that the values of the molecular magnetic moment of films with thicknesses of 4 and 6 nm were close to the theoretical bulk value of magnetite. For the film thickness of 8 nm, larger magnetization was observed probably caused by less oxidation of the deeper Fe layer. The maximum magnetic moment of the film of 2 nm thick was lower due to the structure imperfection. The low coercivity of the films indicated that the quality of the films was reasonably good.
The effects of aluminum doping for the magnetotransport property of Si:Ce thin films
Authors: Shindo D. , Fujii K. , Terao T. , Sakurai S. , Mori S. , Kurushima K. , Fujimura N.
Published: May 2010

Diluted magnetic semiconductor Ce doped Si films with p-type conduction by means of codoping of Al were fabricated with low-temperature molecular beam epitaxy. The uniformly distributed Ce as a magnetic ion is responsible for the disappearance of ferromagnetic nature. Therefore, the magnetotransport properties of the films were investigated if they have any p-f interaction between f electron in Ce and carrier in this DMS sample. The samples with lower carrier concentration (2×1019 cm−3 at 80 K) showed variable range hopping (VRH) conduction and VRH induced magnetoresistance (MR) was recognized. Samples with higher carrier concentration (7×1020 cm−3 at 80 K) showed a metallic conduction and a positive MR. The positive MR is attributed to the quantum correction on the conductivity due to the p-f exchange interaction induced spin splitting of the valence band.
Magnetic properties of gapless semiconductors: PbPdO2 and PbPd0.9Co0.1O2
Authors: Lee K. J. , Choo S. M. , Yoon J. B. , Song K. M. , Saiga Y. , You C.-Y. , Hur N. , Lee S. I. , Takabatake T. , Jung M. H.
Published: May 2010

PbPdO 2 is a new class of gapless semiconductors, which is extremely sensitive to external influences such as temperature, magnetic field, and carrier doping, because of their peculiar band structure. With varying temperature, a broad transition from a high-temperature metallic behavior to a low-temperature insulating behavior was observed at TMI=100 K in the electrical resistivity, which is related to the thermally assisted excitation near the Fermi level due to its gapless band structure. By doping 10% Co for Pd in PbPdO2, the number of hole charge carriers was increased by ten times, and the transition temperature was increased to TMI=150 K. When applying a magnetic field, a ferromagnetic component was found at low temperatures in the magnetization curves of both materials, in addition to diamagnetic background signals for PbPdO2 and paramagnetic background signals for PbPd0.9Co0.1O2. In the low temperature regime, the slope of magnetoresistance is negative, while it is changed into positive with a quadratic form at high temperatures. These results of magnetic properties identify a tendency of strong spin-orbit coupling in the gapless semiconducting compounds.
High-mobility copper-phthalocyanine field-effect transistors with tetratetracontane passivation layer and organic metal contacts
Authors: Kraus Michael , Richler Stefan , Opitz Andreas , Brütting Wolfgang , Haas Simon , Hasegawa Tatsuo , Hinderhofer Alexander , Schreiber Frank
Published: May 2010

We investigate ambipolar charge transport in organic field-effect transistors (OFETs) with copper-phthalocyanine (CuPc) as active material. It is shown that charge carrier mobilities can be increased by at least one order of magnitude using the long-chain alkane tetratetracontane (TTC) as a passivation layer on top of silicon dioxide. TTC and CuPc films are characterized by atomic force microscopy and x-ray diffraction. TTC forms a highly crystalline layer that passivates electron traps on the SiO2 surface very efficiently and serves as a template for the growth of CuPc films with significantly improved crystallinity. High electron mobilities comparable to the values reported on single crystals are reached. We show that the contact resistance for hole transport as determined by the transmission line method can be reduced considerably by using organic charge-transfer complexes as top contacts in OFETs based on CuPc.
Magnetic dead layer in amorphous CoFeB layers with various top and bottom structures
Authors: Jang Soo Young , Lim S. H. , Lee S. R.
Published: May 2010

The magnetic dead layer (MDL) in amorphous CoFeB layers is investigated for four different unit structures. These structures are relevant to the synthetic ferrimagnetic (SyF) free layer structure in magnetic tunnel junctions used for high density magnetic random access memory (MRAM). The MDL results for these unit structures are then converted to those for the constituent interfaces of the SyF free layer structure. These MDL results are critically tested by fabricating the synthetic ferrimagnetic free layer structures with various thickness asymmetries. The observed switching properties of these tested structures are in good agreement with those expected from the effective thicknesses after the MDL correction, confirming the accuracy of the present results for the MDLs at the constituent interfaces.
A two-band model of spin-polarized transport in Fe/Cr/MgO/Fe magnetic tunnel junctions
Authors: Vedyaev A. , Ryzhanova N. , Strelkov N. , Chshiev M. , Dieny B.
Published: May 2010

Theoretical studies of spin dependent transport in Fe/Cr/MgO/Fe tunnel junctions with noncollinear alignment of magnetizations of metallic layers comprising these magnetic tunnel junctions are presented. Calculations are performed with use of nonequilibrium Green function technique in the framework of the Keldysh formalism. Electronic band structure of ferromagnetic electrodes is modeled within a two-band model with majority and minority states being s-like and d-like electrons, respectively. Furthermore, interfacial s-d hybridization is taken into account and calculated using perturbation corrections for the wave and Green functions. It is shown that in the presence of Cr layer at the Fe/MgO interface, the contribution from s-d hybridization to the total current is much stronger in the antiparallel magnetizations configuration compared to the parallel one leading to decrease in tunnel magnetoresistance values in agreement with earlier reports.
Investigation of microstructure and soft magnetic properties of Fe65Co35 thin films deposited on different underlayers
Authors: Li Yanbo , Li Zhenghua , Liu Xi , Fu Yu , Wei Fulin , Kamzin A. S. , Wei Dan
Published: May 2010

Fe 65 Co 35 /underlayer bilayer films were successfully prepared on different underlayer materials (Co93Fe7, Ni80Fe20, Cu, and Fe). The soft magnetic properties of Fe65Co35 films were improved when the texture changed from (110) to (200), which can be controlled by different underlayers. The conversion electron Mössbauer spectroscopy revealed that the angle between the effective magnetization and the normal direction of films with (110) texture is smaller than that with (200) texture. Calculations confirmed that the total anisotropy energy density of Fe65Co35 film with (110) texture is larger than that with (200) texture. Therefore, the soft magnetic properties of Fe65Co35 thin films with (200) texture are better than that with (110) texture.
An algorithm to extract effective magnetic parameters of thin film with in-plane uniaxial magnetic anisotropy
Authors: Neo C. P. , Ding J.
Published: May 2010

The calculation of high frequency complex permeability of thin ferromagnetic film requires the measured values of its saturation magnetization, anisotropic magnetic field intensity, resistivity, and thickness. It is often observed that the calculated permeability using the Landau–Lifshitz–Gilbert (LLG) theory does not agree well with the measured permeability of thin film with in-plane uniaxial magnetic anisotropy, owing to the measured anisotropic magnetic field intensity, saturation magnetization, etc., are not effective values at high frequency. In this work, the Landau–Lifshitz ferromagnetic resonance model is modified to take the skin depth effect into consideration. In the comparison study, its calculated magnetic permeability curves (real and imaginary) agrees very well with those calculated from the LLG model. In addition, an algorithm process to extract effective magnetic parameters (saturation magnetization Ms, magnetic anisotropy field Ha, and damping factor α) has been developed. The algorithm process has been tested for the reported magnetic permeability curves of two magnetic films (Si/NiFe/FeCoB and CoZrRe). The extracted parameters are well agreed with those reported. It is also reported that the consideration of skin depth effect is necessary for samples with lower electrical resistivity.
Determination of negative permeability and permittivity of metal strip coated ferrite disks using the transmission and reflection technique
Authors: Rahman N. , Obol M. , Sharma A. , Afsar M. N.
Published: May 2010

In this paper, a full band microwave isolator constructed from an array of metal wire-coated ferrite samples is presented. Here, the magnetic permeability of the metamaterialized structure is controlled by a relatively weak external magnetic field. The tunable permeability of the ferrites in this experiment allows us to create unidirectional wave propagation through the structure over the entire X-band frequency spectrum. The analysis presented here takes into account potential surface plasmon modes generated between the gaps of metal wires when the external magnetic field is applied. Here, we present a modification of the traditional transmission-reflection measurement method by normalizing the transmission and reflection coefficients. This modification removes the occurrence of atypical phenomena for negative imaginary components of permeability and permittivity that arises in the measurement of metamaterials. Our modified method precisely determines the refractive index, impedance, permittivity, and permeability of both traditional reciprocal networks as well as nonreciprocal networks, such as the one presented here.
Theory of oscillatory tunneling magnetoresistance
Authors: Lee B. C.
Published: May 2010

An analytical form of the oscillatory tunneling magnetoresistance (TMR) is obtained for a magnetic tunnel junction with a single-crystal nonmagnetic layer inserted. The full-band structures are taken into account and the TMR is expressed with spin-dependent reflection amplitudes at the Fermi level and the extremal points. Temperature dependence due to the thermal broadening is included. The phase factor of the reflection amplitude plays an important role in the oscillatory TMR.
Dosimetry of typical transcranial magnetic stimulation devices
Authors: Lu Mai , Ueno Shoogo
Published: May 2010

The therapeutic staff using transcranial magnetic stimulation (TMS) devices could be exposed to magnetic pulses. In this paper, dependence of induced currents in real human man model on different coil shapes, distance between the coil and man model as well as the rotation of the coil in space have been investigated by employing impedance method. It was found that the figure-of-eight coil has less leakage magnetic field and low current density induced in the body compared with the round coil. The TMS power supply cables play an important role in the induced current density in human body. The induced current density in TMS operator decreased as the coil rotates from parallel position to perpendicular position. Our present study shows that TMS operator should stand at least 110 cm apart from the coil.
Multifunctional doxorubicin/superparamagnetic iron oxide-encapsulated Pluronic F127 micelles used for chemotherapy/magnetic resonance imaging
Authors: Lai Jian-Ren , Chang Yong-Wei , Yen Hung-Chi , Yuan Nai-Yi , Liao Ming-Yuan , Hsu Chia-Yen , Tsai Jai-Lin , Lai Ping-Shan
Published: May 2010

Polymeric micelles are frequently used to transport and deliver drugs throughout the body because they protect against degradation. Research on functional polymeric micelles for biomedical applications has generally shown that micelles have beneficial properties, such as specific functionality, enhanced specific tumor targeting, and stabilized nanostructures. The particular aim of this study was to synthesize and characterize multifunctional polymeric micelles for use in controlled drug delivery systems and biomedical imaging. In this study, a theranostic agent, doxorubicin/superparamagnetic iron oxide (SPIO)-encapsulated Pluronic F127 (F127) micelles, was developed for dual chemotherapy/magnetic resonance imaging (MRI) purposes, and the structure and composition of the micellar SPIO were characterized by transmission electron microscopy and magnetic measurements. Our results revealed that the micellar SPIO with a diameter of around 100 nm led to a significant advantage in terms of T2 relaxation as compared with a commercial SPIO contrast agent (Resovist®) without cell toxicity. After doxorubicin encapsulation, a dose-dependent darkening of MR images was observed and HeLa cells were killed by this theranostic micelle. These findings demonstrate that F127 micelles containing chemotherapeutic agents and SPIO could be used as a multifunctional nanocarrier for cancer treatment and imaging.
Nickel related optical centres in diamond created by ion implantation
Authors: Orwa J. O. , Aharonovich I. , Jelezko F. , Balasubramanian G. , Balog P. , Markham M. , Twitchen D. J. , Greentree A. D. , Prawer S.
Published: May 2010

Ni-related optical centres in diamond are promising as alternatives to the nitrogen vacancy (NV) centre for quantum applications and biomarking. In order to achieve the reliability and reproducibility required, a method for producing the Ni-related centres in a controllable manner needs to be established. In this study, we have attempted this control by implanting high purity CVD diamond samples with Ni and N followed by thermal annealing. Samples implanted with Ni show a new Ni-related PL peak centered at 711 nm and a well known doublet at 883/885 nm along with weak NV luminescence. The optical properties of the two Ni-related defects are investigated. In particular, an excited state lifetime of the 883/885 nm peak is measured to be 11.6 ns.
Study of the formation, evolution, and dissolution of interfacial defects in silicon wafer bonding
Authors: Vincent S. , Penot J.-D. , Radu I. , Letertre F. , Rieutord F.
Published: May 2010

Interface defects formed during the wafer bonding process upon annealing have been studied. Based on the hydrogen diffusion in SiO2 and the stability of the bubbles at the bonding interface, models of the growth and further dissolution of the defects are presented. Considering the hydrogen diffusion through the interfacial oxide, diffusion coefficients and activation energy (Ea=0.25 eV) are obtained. It has been shown that the defect dissolution is driven by the exodiffusion of the hydrogen toward the silicon substrates.
Modeling of graphene metal-oxide-semiconductor field-effect transistors with gapless large-area graphene channels
Authors: Thiele S. A. , Schaefer J. A. , Schwierz F.
Published: May 2010

A quasianalytical modeling approach for graphene metal-oxide-semiconductor field-effect transistors (MOSFETs) with gapless large-area graphene channels is presented. The model allows the calculation of the I-V characteristics, the small-signal behavior, and the cutoff frequency of graphene MOSFETs. It applies a correct formulation of the density of states in large-area graphene to calculate the carrier-density-dependent quantum capacitance, a steady-state velocity-field characteristics with soft saturation to describe the carrier transport, and takes the source/drain series resistances into account. The modeled drain currents and transconductances show very good agreement with experimental data taken from the literature {Meric et al., [Nat. Nanotechnol. 3, 654 (2008)] and Kedzierski et al., [IEEE Electron Device Lett. 30, 745 (2009)]}. In particular, the model properly reproduces the peculiar saturation behavior of graphene MOSFETs with gapless channels.
Experimental tests of a magnetostrictive energy harvesting device toward its modeling
Authors: Adly Amr , Davino Daniele , Giustiniani Alessandro , Visone Ciro
Published: May 2010

This paper deals with a recently proposed device for energy harvesting from environmental vibrations, employing a magnetostrictive material. Even if most of the modeling efforts were focused on a linear approach, more complex and nontrivial phenomena are experimentally observed. A sample of such nontrivial behaviors, suggesting the definition of potentially more effective models, is described and discussed in this paper.
Magnetic and optical properties of multiferroic GdMnO3 nanoparticles
Authors: Wang X. L. , Li D. , Cui T. Y. , Kharel P. , Liu W. , Zhang Z. D.
Published: May 2010

The magnetic and optical properties of multiferroic GdMnO3 nanoparticles synthesized by a polymerized complex method have been investigated. The GdMnO3 nanoparticles crystallized in orthorhombic perovskite-type structure. The zero-field-cooled and field-cooled magnetizations show that complicated magnetic transitions occur in a temperature range from 2 to 60 K, which were confirmed by magnetic hysteresis loops. Three shoulder absorption peaks centered at about 2.0, 2.3, and 2.7 eV are attributed to the Mn (3d)-electronic transitions, while an absorption peak at around 4.1 eV corresponds to the charge-transfer transitions between O (2p) and Mn (3d) states. UV emission at about 396 and 406 nm and blue emission at around 466 nm have been found, which may be attributed to the spin-allowed charge-transfer transitions.
Structural and magnetic characterizations of high moment synthetic antiferromagnetic nanoparticles fabricated using self-assembled stamps
Authors: Koh Ai Leen , Hu Wei , Wilson Robert J. , Earhart Christopher M. , Wang Shan X. , Sinclair Robert
Published: May 2010

High-moment synthetic antiferromagnetic (SAF) nanoparticles were produced using 4 in. diameter stamps made by self-assembly and nanosphere lithography of latex nanospheres. This leads to a significant increase in particle yield over a pre-existing technique which utilizes a 1 cm2 stamp patterned using e-beam lithography. Changes in nanopillar dimensions from the self-assembled stamps and variations in the associated processing conditions can lead to the fabrication of particles with different dimensions. We demonstrate that it is possible to produce reasonably uniformly sized SAFs with diameters from 70 nm upward using self-assembled stamps. The particles exhibit low remanence at low externally applied magnetic fields, and that the saturation magnetization more than double that for conventional iron oxide nanoparticles.
Magnetic properties of TbFeCo-based perpendicular magnetic tunnel junctions
Authors: Lee Ching-Ming , Ye Lin-Xiu , Hsieh Tung-Hsien , Huang Chao-Yuan , Wu Te-Ho
Published: May 2010

The perpendicular magnetic tunnel junctions of structure Si/Ti(10 nm)/TbFeCo(22 nm)/CoFeB(2 nm)/MgO(1 nm)/CoFeB(1 nm)/TbFeCo(3 nm)/Ti(10 nm) were deposited on SiNx substrates at room temperature with various Tb contents. The samples were then annealed at different temperatures ranging from 150 to 350 °C. We found that the magnetic tunnel junctions with free-layer Tb content near the compensation point show largest coercivities and best squareness, and more important, best annealing endurance. The maximum magnetoresistance ratio is 4.62% for Tb content 19.7% as deposition. Annealing treatment cannot increase MR further because no crystalline MgO structures were present, even though the samples were annealed up to 350 °C.