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The lithium ion dynamics in graphite, an important anode material for lithium ion batteries, is strongly related with the layer-to-layer distance (d-spacing) and the stacking modes of graphite. We studied these relationships by first-principles calculations. It is found that a larger d-spacing results in the easier transformation of the stacking mode from A-B stacking to A-A stacking when lithium atoms are inserted. This transformation is unfavorable to the lithium diffusion because of the larger diffusion energy barrier for lithium in A-A stacking graphite compared to that in A-B one. On the other hand, as the d-spacing increases, the diffusion energy barrier for lithium in A-A stacking graphite decreases substantially, thus being favorable to the lithium diffusion. These results give a better understanding of the lithium ion dynamics in graphite, and show that it is possible to optimize the lithium ion dynamics in graphite by properly adjusting the d-spacing. [ABSTRACT FROM AUTHOR]

This study experimentally demonstrates a superconducting detector that can be switched for charge signal and superconducting phase signal detection by tuning a magnetic field. In zero magnetic field, the one-dimensional array of superconducting quantum interference devices exhibits superconducting coherency and is phase sensitive. The array may become insulating and charge sensitive when a small perpendicular magnetic field is applied. [ABSTRACT FROM AUTHOR]

We have studied the microstructure of SrTiO[sub 3] films on LaAlO[sub 3] substrates with the SrRuO[sub 3] buffer layer using high-resolution transmission electron microscopy. While high density of defects due to lattice mismatch were found at the SrRuO[sub 3]/LaAlO[sub 3] interface, no misfit dislocation was observed at the SrTiO[sub 3]/SrRuO[sub 3] interface. The {111} stacking fault in the SrRuO[sub 3] buffer layer propagates into the SrTiO[sub 3] film, giving rise to a type of antiphase boundary on the {110} plane with a crystallographic shear vector of a/2<001>. The boundary is a conservative one which does not lead to any charge defects. A model based on dislocation interactions is proposed to explain the generation mechanism of the antiphase boundary. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Properties of fragmentation from an explosively driven 316L stainless steel spherical shell section fabricated by a laser powder bed additive manufacturing process with minimal surface finishing are investigated. This shell is driven by an insensitive high explosive, resulting in high strain rate deformation (>8 × 103 s−1) and failure of the stainless steel. Photonic Doppler velocimetry measures the expansion rate; dynamic radiography and high-speed imaging capture the fracture behavior of the stainless steel. The fracture response of the additively manufactured stainless steel shell is compared to published experimental results on additively manufactured 316L stainless steel and conventionally manufactured wrought 316L and 304 stainless steel shell fragmentation. Despite preferred crack orientation, suggesting the influence of surface grooves on fracture time, fragment size is identical to that measured in a similar experiment on wrought 304 stainless steel. Further analysis indicates that the 316L additively manufactured stainless steel shell exhibits comparable spall strength and fragmentation toughness to conventionally manufactured stainless steel yet lower failure strain due to surface stress concentrations. [ABSTRACT FROM AUTHOR]

Investigates the effects of germanium in the erbium film on the barrier height. Sample preparation; Role of an interfacial layer in barrier formation.

Presents an overview of a study on erbium and erbium-silicon contacts on p-silicon. Correlation between the barrier height and the presence of an interfacial oxide layer; Barrier heights determined by current-voltage measurements; Application of the nuclear reaction technique.

Investigates oxygen on cadmium-tellurium substrates by means of x-ray photoelectron spectroscopy and reflection high-energy electron diffraction. Details on the experiment; Results of the study; Conclusions.

Presents the results of an investigation on the tellurium-stabilized and the cadmium-stabilized surfaces of (100) cadmium telluride substrates. Effect of laser illumination on the cadmium telluride growing surface; Discussion of results.

Deals with a study which examined the x-ray photoelectron spectroscopy of cadmium telleride and gallium arsenite interfaces. Information on the thin films; Methodology of the study; Results and discussion.

Focuses on a study which proposed a novel operation in the vertical integration of double-barrier resonant tunneling structures (DBRTS) in which the negative differential resistance region can be repeated. Applications of DBRTS; Cross section of the vertically integrated DBRTS; Characteristics of a finished device.

Prepares the hydrogenated amorphous germanium carbide films by radio frequency (rf) sputtering at various rf power levels and mixtures of argon, hydrogen[sub2], and propane. Measurement of film thickness; Auger spectra of several samples; Concentration of hydrogen bonded to carbon.

A pure compressively strained La2/3Ca1/3MnO3 (LCMO) dead layer grown on (001)-oriented LaAlO3 substrate can show all the rich phenomenon of large bias field shift, coercive field enhancement, and high blocking temperature. The obtained exchange bias field (~350 Oe) and the enhanced coercivity of about 1160 Oe at 5K under 500 Oe cooling field are superior to that have been reported in LCMO-based ferromagnetic/antiferromagnetic superlattices or nanoscale systems. Our results clearly demonstrate that the inhomogeneous magnetic dead layer of LCMO can induce a strong exchange bias effect, which may be exploited as a very simple structure for spin-valve device application. [ABSTRACT FROM AUTHOR]

Effects of cation disorder and strain on the surface morphologies and transport properties of thin films with different A-site cation disorder, which was achieved by Y and Sr codoping into La2/3Ca1/3MnO3, have been investigated. A metal-insulator transition (MIT) was observed on all films except that on MgO, which indicates that large strain increases insulator phase. With increasing cation disorder, the resistivity increases while MIT and Curie temperature decrease, which reveal that cation disorder suppresses the long-range ferromagnetic metallic phase. The spin-glass state and ferromagnetic-metallic state coexist in low temperature. Cation disorder induces more insulator phases in the large strain films. A Kondo-like transport behavior was observed in the large cation disordered films. [ABSTRACT FROM AUTHOR]

La2/3Ca1/3MnO3 (LCMO)/YBa1.8Eu0.2Cu3O7 (YBECO) multilayers on yttrium-stabilized ZrO2 are fabricated. YBECO sublayer is well crystallized in c-axis orientation, while LCMO sublayer crystallized in (001) textured structure, which forms special mosaic structure. By magnetization measurements, we confirm that the cluster spin glass existed in LCMO/YBECO multilayers in low temperature, which may scatter the transport electrons. Superconductivity cannot be observed when thickness of YBECO layer is less than 24 nm. The magnetoresistance ratio depends on the thickness of YBECO layer. The magnetotransport properties of the multilayers make it very promising to provide a technological support for the heterostructure and superlattice of manganites and superconductors. [ABSTRACT FROM AUTHOR]

YBa2Cu3O7-δ (YBCO) powders with Gd2O3 additives are prepared by the solid state reaction method. X-ray diffraction with Rietveld refinements shows that both Gd2O3 and YBCO phases coexist in the products. With increasing additive content, the unit cell symmetry of YBCO phase remains unchanged but the grain size increases. The critical current density (Jc) exhibits a maximum at x=0.1 in YBCO+ xGd2O3 systems. Moreover, the addition of Gd2O3 in YBCO enhances Jc by applying the magnetic field, although the superconducting temperature (Tc) decreases slightly. We argue that the characteristic behavior of Jc may come from the counterbalance of two effects simultaneously, which was caused by the variation of superconductivity and the inhomogeneity of grain distribution in nanoscale. [ABSTRACT FROM AUTHOR]

The interface structure and magnetoresistance (MR) for the single spin valve (SV) of Co/Cu/Co structure with a NiO layer at the top or under the bottom were investigated. Glancing incident x-ray reflectivity and x-ray diffuse scatter studies show that the interface roughness of NiO on Co is much larger than that of Co on NiO. The large roughness may be one of the main factors of suppressing spin reflectivity. The interface between NiO and Co becomes more flat after annealing. Different temperature dependence of MR was observed for the top and the bottom SV. We attribute the above phenomena to the competition between the roughness and the exchange effects of the NiO/Co interface. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

La0.67Ca0.33MnO3 (LCMO) thin films with the thickness varying from 200 to 500 Å have been deposited by magnetron sputtering on sapphire, SrTiO3, yttrium-stabilized ZrO2 substrates. A metal-to-insulator transition behavior was observed for all samples with the transition temperature and width varying with the substrate and the film thickness. A percolation model has been used to obtain the physical parameters on low-temperature metallic transport behavior and the adiabatic thermal small polaron hopping progress. The surface of the deposited films was measured by atomic force microscopy and grazing incidence x-ray specular and diffuse scattering. Fits to the data show the presence of a mixed layer between the substrate and the LCMO films the extent of which depends on the substrate used. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Thin Yba[SUB2]Cu[SUB3]O[SUB7-δ/La[SUB0.67]Ca[SUB0.33]MnO[SUB3] (YBCO/LCMO) films were grown on SrTiO[SUB3](STO)substrates by magnetron sputtering technique. The microstructures of the bilayers were characterized and a standard four-probe technique was applied to measure the resistivity of the samples. The interdiffusions at the YBCO/LCMO and LCMO/STO interfaces formed two transient layers with the thickness of about 3 and 2 nm, respectively. All the bilayers were well textured along the c axis. At low temperature, the superconductivity can only be observed when the thickness of YBCO is more than 25 nm. When the thickness of YBCO is less than 8 nm, the bilayers show only ferromagnetism. The superconductivity and ferromagnetism perhaps coexist in the bilayer with the YBCO thickness of 12.5 nm. These interesting properties are related to the interaction between spin polarized electrons in the manganites and the cooper pairs in the cuprates. [ABSTRACT FROM AUTHOR]

Microstructured rare-earth-transition-metal DyFeCo films have been investigated using magnetoresistance and extraordinary Hall-effect measurements. The Hall loops reveal variation of coercive fields depending on the linewidth and the composition of the films. The magnetoresistance curves, with changes up to as high as 1.3%, show positive/negative magnetoresistance peaks centered on the coercive fields depending on the linewidth of the films only. The variation of the coercivity can be attributed to the magnetic moment canting between the Dy and FeCo subcomponents and the existence of the diverged magnetization on the edges, and the anomalous magnetoresistance peaks observed are discussed with the existing theories. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Reports on a study which demonstrated the use of sputtered silicon films in developing etching masks for gallium arsenide devices. Materials commonly used for etching masks; Preparation of the silicon films; Conclusion.

The double-wave method is widely used in ferroelectric measurements to eliminate the effects of conductance and capacitance components while preserving the ferroelectric domain contribution. However, in polycrystalline ferroelectric material, the assumption of the evolution of domains by the double-wave method no longer applies due to the domain back switch of de-field, and the domain contribution calculated by the current subtraction method is also problematic. Therefore, we proposed a new method to calculate the charge contribution of conductance and eliminate the conductance interference in the hysteresis loop. Finally, the feasibility of this new method is verified in many typical polycrystalline ferroelectric materials. This work provides a path for the study of ferroelectric properties of some high conductivity materials. [ABSTRACT FROM AUTHOR]

Deals with a study which detailed the enhancement of peak-to-valley current ratios of double-barrier resonant tunneling structures based on the AlGaAs/GaAs material system. Cause of the size quantization of the accumulation layer; Characteristics of double-barrier resonant tunneling structures; Result of the quantum effect of the two-dimensional electrons accumulated near the source electrode.

The structural and magnetic properties of high κ dilute magnetic oxides (DMOs) have been studied in two types of samples: thin films and nanocrystals, including Co doped HfO2 films, Co doped Y2O3 films, Co doped Y2O3 nanocrystals, and Mn doped Y2O3 nanocrystals. The characterizations were conducted by extended x-ray absorption fine structure, x-ray absorption near edge structure, and superconducting quantum interference device vibrating sample magnetometer. Oxygen vacancies are shown to play a crucial role in ferromagnetic ordering, as defect centers in the bound magnetic polaron model to account for DMOs with medium band gap and low carrier concentration. The observation of room temperature ferromagnetism in tri-valence oxide of Y2O3 as well as in tetra-valence oxide of HfO2 suggests a generic feature of transition metal doped high κ oxides as good candidates for DMO. The ability to modulate the magnetic behavior of DMO via oxygen vacancy concentration by means of post anneals can be exploited for potential applications in spintronics. [ABSTRACT FROM AUTHOR]

Perfect and defective surface structures for (001) SrTiO3 are determined in considering a supercell with 11 atomic layers using the first-principles calculations. The amplitude of the surface rumpling for the SrO-terminated surface is much larger than that for the TiO2-terminated surface, although both SrO- and TiO2-terminated surfaces are stable for a comparable range of the TiO2 chemical potential. The distance between the first and second planes compresses while that of the second and third planes expands due to the relaxation of the slab. The top sites of the oxygen atoms of SrO-termined surface and the fourfold symmetry hollow sites of TiO2-termined surface are favorable for Ti or Sr adsorbate. The relative stability of the defect species or reactions varies with the equilibrium conditions. The dominant surface defect is Ti substitutional defect and a TiO–TiO2 double layers may form at the surface, which has been confirmed by experiments. [ABSTRACT FROM AUTHOR]

We present a systematic study of temperature-dependent reflectance (R) and photoluminescence (PL) measurements on ZnMnO films grown by plasma-assisted molecular beam epitaxy. For the first time, the three free-exciton transitions FXA (Γ7c-Γ7vu), FXB (Γ7c-Γ9v), and FXC (Γ7c-Γ7vl) and the longitudinal-optical phonon replicas of FXB and FXC of ZnMnO films have been clearly observed in the R spectra. The parameters describing the activation energy and the temperature dependence of the transition energy and broadening have been extracted by fitting the experimental R and PL spectra. The spectral data of ZnMnO films not only show the deterioration of crystalline quality with increasing Mn composition fraction but also indicate the Mn clustering caused by Mn atom segregation. [ABSTRACT FROM AUTHOR]

The lattice parameter and electronic structures of CoSi and CoSi1-xYx (Y=Al and P, x=0.031 25 and 0.125) were calculated using the full-potential linear augmented plane wave approach based on density functional theory. The calculated lattice parameter of binary CoSi is about 0.27% smaller than the experimental value. Calculated electronic structures show that CoSi is a semimetal and its density of states is very small at the Fermi level. Doping with Y on the Si site can tune the Fermi level and the effective masses as well as the density of the hole carriers or electron ones in the electronic structure of CoSi, which is a valuable way to modulate the transport properties of this compound. Based on the calculated electronic structures and our experimental results on CoSi, the intrinsic relations between the electronic structures and transport properties of doped and undoped CoSi are discussed in detail. [ABSTRACT FROM AUTHOR]

We report the band structures as well as frequency-dependent (dynamic) linear and nonlinear optical properties of CsCdBr3 and RbCdI3·H2O crystals calculated within density functional theory with a nonlocal gradient correction, including the dielectric function, linear and nonlinear refractive indices, frequency doubling, and self-focusing of light. The electronic origin of the optical susceptibilities is described and the critical power of light self-focusing is estimated for these two crystals. [ABSTRACT FROM AUTHOR]

Hexagonal yttrium manganite (YMnO3) and chromium doped yttrium manganite (YMn1 – xCrxO3) were prepared by the solid-state method. X-ray diffraction and Raman scattering were combined to explore the structural characterization. Structural analysis illustrates that the lattice is compressed and the tilt of the MO5 (M = Cr or Mn) bipyramid is decreased with an increase in Cr3+ concentration, leading to declining frustration. Magnetic measurement suggests both weak ferromagnetic (FM) and antiferromagnetic (AFM) orderings enhanced with the growth of doping concentration. Enhanced weak FM ordering may arise from breaking of the superexchange interaction and introduction of the double-exchange interaction inside the layers, and the increased AFM ordering is attributed to the improved coupling between neighboring planes that resulted from the structural distortion. Spin-phonon coupling is discussed to confirm the enhanced coupling between interplane Mn3+ moments. [ABSTRACT FROM AUTHOR]

Laser-induced femtosecond demagnetization, femtomagnetism, offers a potential route to develop faster magnetic storage devices. It is generally believed that the traditional spin-wave theory, which is developed for thermally driven slow demagnetization, cannot explain this rapid demagnetization by design. Here, we show that this traditional spin-wave theory, once augmented by laser-induced spin–orbit torque, provides a highly efficient paradigm for demagnetization, by capturing low-energy spin-wave excitation that is absent in existing mechanisms. Our paradigm is different from existing ones but does not exclude them. Microscopically, we find that optical spin–orbit torque generates massive spin waves across several hundred lattice sites, collapsing the long-range spin-spin correlation within 20 fs. Our finding does not only explain new experiments but also establishes an alternative paradigm for femtomagnetism. It is expected to have far-reaching impacts on future research. [ABSTRACT FROM AUTHOR]

Presents information on a study which examined the growth kinetics and surface morphology of erbium silicide formation from erbium layers on silicon(100) substrates using e-beam annealing and furnace annealing. Measurement of the kinetics of erbium silicide formation; Experimental details; Results and discussion; Conclusions.

High performance pseudomorphic In[sub x]Ga[sub 1-x]As/GaAs modulation doped field effect transistors (MODFETs) grown by metalorganic chemical vapor deposition have been characterized at dc using modulation spectroscopy. A transconductance as high as 175 and 253 mS/mm was obtained at 30% and 40% indium content, respectively. In order to identify the origin of the MODFETs' features we have performed a self-consistent Schrodinger—Poisson calculation of the subband and intersubband energies. The photoreflectance spectra can be divided into two parts by the photon energy; one belongs to the GaAs bulk transition and the other belongs to the InxGa[sub 1-x]As/GaAs quantum well transition including two-dimensional electron gas (2DEG) signals. The built-in electric fields are 20.6x 10[sup 4] V/cm and 22.6x10[sup 4] V/cm. From photoreflectance spectra peaks at 1.035 and 1.06 eV show that their energies agree with line shape fitting and 2DEG theory. © 1997 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study that examined thin iron-oxide films deposited in situ on substrates by direct current-reactive magnetron sputtering method. Use of post-oxidation treatment and bending-beam method; Effect of residual stress on the coercivity of the films; Schematic illustration of the experimental setup of the bending-beam apparatus used for stress measurement.

Determines the aluminum (Al) composition of AlGaAs by various methods. Preparation of the AlGaAs layers; Way to obtain the Al mole fraction; Purpose of the reflection high-energy electron diffraction intensity oscillation; Formula for the Al mole fraction of the AlGaAs from the photoluminescence method.

Presents a study that reported the effects of growth temperature on metalorganic chemical vapor deposition-grown In[sub x]Ga[sub 1-x]Sb epitaxial quality and the variation of x with growth temperature. Details of the experiment; Results and discussion; Conclusions.

Presents a study which developed a model based on analytical expressions that describe the reduction of the cutoff of heterojunction bipolar transistors due to high current densities in the collector layer. Advantages of using compound-semiconductor heterojunction bipolar transistors; Description of the physical mechanisms occurring in the collector layer; Discussion on the conventional theory of the cutoff frequency.

Presents a study which examined the application of a semiempirical self-consistent-field band calculation to near-edge fine-structure analysis of core-shell electronic absorption edges. Methods; Results; Discussion.

Presents a study that investigated the ion implantation tailoring of electrically active dopant profiles gallium arsenide. Details of the experiment; Results and discussion.

Describes the application of thin silicon (Si) films for selective area Si and zinc (Zn) diffusion into gallium arsenide and AlGaAs. Advantage of the Si film; Details on the Zn diffusion with the Si mask.

Structure and transport properties of Eu-doped YBa2-xEuxCu3O7-δ (YBECO) have been studied. Eu is confirmed preferring to replace Ba at Ba sites. The averaged valence state of Eu, which is examined by x-ray photoemission spectroscopy, increases with increasing x. Eu doping in YBECO has a little influence on superconductivity in our studies, and the superconducting transition temperature Tc is almost unchanged. [ABSTRACT FROM AUTHOR]

We studied the microstructures, electronic, and magnetic properties on La-doped and La- and Ca-codoped YBa2Cu3O7-δ (YBCO). The superconducting transition temperature remains unchanged up to 10% for La-doped YBCO. The competition between electrons and holons was assumed according to the variation of Tc0 in La and Ca codopings in YBCO. The magnetoresistance (MR) effect is about 8%, which is observed obviously near the critical temperature and is independent of the content of La in La-doped YBCO. MR increases up to about 40% with the incorporation of Ca in La-doped YBCO. We present here possible explanations for the magnetoresistance effect in polycrystalline samples based on the microstructure and the increase of oxygen vacancies at grain-boundary interface. [ABSTRACT FROM AUTHOR]

Structural, magnetic, and calorimetric properties are reported for the La[sub 1-x]Pr[sub x]Ba[sub 2]Cu[sub 3]O[sub 7] solid solution. The structure remains orthorhombic with lattice parameter increases from a=0.3872, b=0.3927, and c=1.1709 nm for PrBa[sub 2]Cu[sub 3]O[sub 7] to a=0.3903, b=0.3944, and c=1.1801 nm for LaBa[sub 2]Cu[sub 3]O[sub 7]. Substitution of Pr for La depresses T[sub c] from 90 to 52 K for La[sub 0.5]Pr[sub 0.5]Ba[sub 2]Cu[sub 3]O[sub 7], which was reported to be a nonsuperconductor. The Pr antiferromagnetic ordering temperature T[sub N] decreases monotonically from 18 K for PrBa[sub 2]Cu[sub 3]O[sub 7] to 6 K for La[sub 0.8]Pr[sub 0.2]Ba[sub 2]Cu[sub 3]O[sub 7]. Thus there is a large range of coexistence of superconductivity and antiferromagnetism for 0.2≤x≤0.5. The superconductivity and anomalous Pr ordering will be discussed with the R[sub 1-x]Pr[sub x]Ba[sub 2]Cu[sub 3]O[sub 7] systems (R=Y, Nd-Lu). © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report on the study of high frequency magnetotransport properties of the chromium dioxide (CrO[sub 2]) thin films, grown on Si substrate using chemical vapor deposition. The film exhibits a ferromagnetic transition with a Curie temperature near 390 K. The temperature dependent spontaneous magnetization follows Bloch's law. The impedance spectra, being analyzed based on the fundamental electrodynamics, are demonstrated to be in a low-loss dielectric limit along with the occurrence of dielectric relaxation and magnetization response. The specific features of impedance spectra, distinct from the usual metallic ferromagnet, are attributed to the half metallic nature of CrO[sub 2]. The results explore the possibility for high frequency device applications. [ABSTRACT FROM AUTHOR]

A series of polycrystalline YMn1-xRuxO3 (0≤x≤0.2) samples were prepared by traditional solidstate reaction method. Effects of doping on the microstructures and magnetic properties were investigated. Microstructural results reveal that samples crystallize in a single hexagonal structure with P63cm group for x≤0.1. Lattice parameters a, c, and unit-cell volume of YMn1-xRuxO3 are found to increase with doping content, which are ascribed to the larger radius of Ru3+ than that of Mn3+. Weak ferromagnetism is found and is enhanced with increasing doping concentration x. The bond angles of Mn-O3-Mn and Mn-O4-Mn are changed in the opposite trends, which break the Mn-Mn exchange interaction, thus the antiferromagnetic ordering. The MnO5 bipyramid is found to be relieved and the trimerization of Mn ions is weakened. These structural modifications result in the increase of weak ferromagnetism ordering in samples. [ABSTRACT FROM AUTHOR]

The structural, electronic, and magnetic properties of (La2/3Sr1/3MnO3)m/(SrRuO3)n superlattices have been investigated based on the first principles calculations. An obvious Jahn-Teller distortion, which depends on m, n, appears in MnO6 octahedron in the superlattices. The stretch along c-axis of MnO6 octahedron at the interface lifts the Mn eg orbital degeneracy, with electrons preferring the lower energy 3z2 - r2 to the higher energy x2 - y2. Benefitting from the charge transfer at the interface, the still occupied x2 - y2 orbital can mediate a robust in-plane double exchange interaction. La2/3Sr1/3MnO3 block is ferromagnetic and metallic, even for the superlattice with m=n=1. [ABSTRACT FROM AUTHOR]

LaMnO3+δ films with various thicknesses were grown on LaAlO3 (001) single crystal substrate to investigate the effect of in-plane compressive strain (~-0.57%) on magnetic properties. All films exhibit a blocking temperature Tb at which the zero field cooled magnetization reaches a maximum, indicating the ferromagnetic (FM) nanoclusters are embedded in the background of antiferromagnetic (AFM) matrix. The onset temperature of FM transition Tc and Tb is increased by 24% and 89%, respectively, with the thickness decreasing from 82.4 nm to 9.2 nm. Simultaneously, the saturation magnetization greatly increases by 309%, which is ascribed to the strain-induced transition of AFM to FM phase due to the orbital order structure switching from x²- 1/y²-1 [A-type] to (x²- y²) + (z²- 1) [F-type]. [ABSTRACT FROM AUTHOR]

Shot noise, which accompanies the emergence of the quantization nature (discreteness) of electrons, indicates dynamic fluctuations in electrical current and further reveals underlying operations in mesoscopic applications. This work presents a multichannel junction device with which to study the shot noise of coupled-channel transports as in normal nanocircuits, and it describes the theoretical algorithms. The numerical results show that, in contrast to the indistinguishable results of average current on direct-current measurements, the shot noise related to a dynamic current definitely exhibits significant differences among devices with diverse multichannel set-ups and presents super-Poissonian behaviors associated with the splitting of tunneling states. [ABSTRACT FROM AUTHOR]

Structural, magnetic, and ferroelectric properties have been investigated for Bi2Fe4(1-x)Ti4xO9 (0≤x≤0.2) bulk ceramics, which were synthesized by a modified Pechini method. X-ray diffraction reveals that all samples are single phase with no impurities detected. Compared with antiferromagnetic Bi2Fe4O9 compound, doping with Ti ions induces the appearance of weak ferromagnetism at room temperature, which is discussed in terms of the collapse of the frustrated antiferromagnetic spin structure. Moreover, appropriate Ti doping also significantly reduces electric leakage and leads to the enhancement of electrical polarization. Among all samples, the optimal multiferroics with Mr∼0.0188 emu/g and Pr∼0.262 μC/cm2 at room temperature is found for x=0.15 ceramics. It is thus shown that Ti-doped Bi2Fe4O9 is a promising candidate for preparing multiferroic materials. [ABSTRACT FROM AUTHOR]

For a single weak-coupled Josephson junction, stochastic Cooper-pair tunnelings drive the superconducting current on low voltage biases, while quasiparticle tunnelings stimulate the normal current on high biases above the superconducting gap voltage. Considering these interactive dynamics simultaneously in one-dimensional weak-coupled Josephson arrays in electrodynamic environments, the theoretical work by rate equations is structured herein, and the charge transport associated with short-range (Cooper pair and quasiparticle) and long-range (Cooper-pair soliton and quasiparticle soliton) behaviors is analyzed. [ABSTRACT FROM AUTHOR]

The structural, magnetic, and electric properties of Dy1-xSrxCoO3-δ perovskite have been investigated systematically over the range of doping, 0.65≤x≤0.90. The Rietveld refinements of x-ray powder diffraction patterns at room temperature indicate that the samples with 0.65≤x≤0.75 show a tetragonal structure with I4/mmm group symmetry, while the compounds with 0.80≤x≤0.90 are cubic with pm3m group symmetry. Zero field-cooled magnetization, M(T), of 0.65≤x≤0.85 samples reveals a cusp at around room temperature. For all samples, M(T) increases rapidly below 50 K due to the paramagnetism of Dy sublattice. The inverse magnetic susceptibility, χ-1(T), was described by using Curie–Weiss law. The resistivity (ρ) data can be explained according to a three-dimensional variable range hopping model in a certain temperature range. The density of states at the vicinity of Fermi level is roughly estimated. [ABSTRACT FROM AUTHOR]

Polycrystalline Si1-xMnx thin films codoped with boron have been fabricated by sputtering technique followed by postcrystallization processes. Structural, magnetic, and transport properties of the films were investigated. Magnetic property investigation indicated that the films consist of two ferromagnetic phases. The low Curie temperature ferromagnetic phase (TC∼50 K) is due to the Mn4Si7 phase in the films as detected by x-ray diffraction, while the high temperature one (TC∼250 K) is resulted from the incorporation of Mn into silicon. It has been found that, with carriers confirmed as p type, for the same effective concentration of Mn the saturation magnetization of the films with higher carrier concentration is higher than that of those with lower carrier concentration, which suggests a mechanism of hole-mediated ferromagnetism for Si-based diluted ferromagnetic semiconductors. [ABSTRACT FROM AUTHOR]