Long-range State Research Articles

Inter- and Intra-granular Interactions of REBa2Cu3O7−δ , RE: Eu, Gd, Ho and Er

Here, the superconducting and AC/DC magnetic properties of REBa2Cu3O7−δ (RE: Eu, Gd, Ho and Er) are investigated in order to understand the inter-granular and intra-granular behavior of these compounds. These compounds were prepared by standard solid-state reaction route. ErBa2Cu3O7−δ (Er-123) and HoBa2Cu3O7−δ (Ho-123) (consisting of heavier rare earth) show higher orthorhombic splitting in their XRD patterns than those observed for EuBa2Cu3O7−δ (Eu-123) and GdBa2Cu3O7−δ (Gd-123) (consisting of lighter rare earth). Even though Eu, Gd, Ho and Er are magnetic elements, substitution of these at Y site in Y-123 does not change the superconducting transition temperature (T c). Er-123 and Ho-123 exhibit very sharp superconducting transition while Eu-123 and Gd-123 exhibit relatively broad transition with little hump at the lower part of transition close to the long-range superconducting state with zero resistance. In addition to that, Eu-123 and Gd-123 show relatively higher normal state resistivity than those of Er-123 and Ho-123. The AC susceptibility measurements reveal that these compounds possess different strength of inter-granular couplings. The hump in the superconducting transition of Eu and Gd is not due to the lack of inter-grain couplings in these samples because of having better grain connectivity in the samples as compared to other rare earth elements in REBa2Cu3O7−δ system. Though intra-grain peak is insensitive to the applied magnetic field, inter-grain peak is sensitive to the applied magnetic field.

Neutron Scattering Study of the Long-Range Ordered State in CeRu2Al10

Elastic and inelastic neutron scattering measurements have been performed on powder and single-crystal samples of orthorhombic CeRu 2 Al 10 . The order forming below T 0 = 27 K was identified as a long-range antiferromagnetic state with the wave vector k = (1,0,0). The magnetic spectral response in the ordered phase, measured on powder, is characterized by a spin gap and a pronounced peak at 8 meV, whose Q dependence suggests a magnetic origin. Both features are suppressed when temperature is raised to T 0 , and a conventional relaxational behavior is observed at 40 K. This peculiar spin dynamics is discussed in connection with recent magnetization results for the same compound.

Structural and magnetic properties and evidence of spin-glass behavior induced by Fe-doping in perovskite manganites B-site

AMn 1 − x Fe x O 3 ( A = La 0.75 Ca 0.08 Sr 0.17 and x = 0–0.23 ) compounds, sintered at 700 °C , were characterized by X-ray diffraction (XRD) at room temperature. Rietveld refinement has shown that samples can be indexed in the orthorhombic ( Pnma) structure for low Fe-content ( x ≤ 0.046 ) and rhombohedral ( R - 3 c ) structure for high Fe-content ( x ≥ 0.115 ). The transmission Mössbauer spectra have revealed the same isomer shift δ value assigned to Fe 3+ ion for all compounds. The magnetization behavior and the Curie temperature T C have shown a large dependence on the fractional composition x. In fact, the M(T) curves have revealed the presence of a long-range ferromagnetic state below T C for compounds with x ≤ 0.115, and a spin-glass state (SGS) at low temperature for high Fe-content ( x ≥ 0.177).

Sequential Labeling Using Deep-Structured Conditional Random Fields

We develop and present the deep-structured conditional random field (CRF), a multi-layer CRF model in which each higher layer's input observation sequence consists of the previous layer's observation sequence and the resulted frame-level marginal probabilities. Such a structure can closely approximate the long-range state dependency using only linear-chain or zeroth-order CRFs by constructing features on the previous layer's output (belief). Although the final layer is trained to maximize the log-likelihood of the state (label) sequence, each lower layer is optimized by maximizing the frame-level marginal probabilities. In this deep-structured CRF, both parameter estimation and state sequence inference are carried out efficiently layer-by-layer from bottom to top. We evaluate the deep-structured CRF on two natural language processing tasks: search query tagging and advertisement field segmentation. The experimental results demonstrate that the deep-structured CRF achieves word labeling accuracies that are significantly higher than the best results reported on these tasks using the same labeled training set.

Determination of the rotational constant of the Cs_2 0_g ^- (6s + 6p_3/2) state by trap loss spectroscopy

we demonstrated a high sensitive trap-loss spectroscopy technique by modulating fluorescence of cold atoms in magneto-optical trap, which allow a direct spectroscopy detection of the rovibrational levels with a very weak transition probability. The low-lying vibrational spectroscopy of upsilon = 3 approximately 17 of Cs(2) 0g- pure long-range state have been observed with rotational structures, which are well resolved up to J = 8. The rotational constants are obtained by fitting experimental data to a nonrigid rotation model.

Ferromagnetism in nitrogen-doped cubic ZrO 2: Density-functional investigations

Stable ferromagnetism in nitrogen-doped cubic ZrO 2 is reported based on first-principles calculations. A substitution of oxygen by nitrogen introduces spin-polarized 2 p states near the Fermi level, producing a total magnetic moment of 1.0 μ B . The hole-mediated direct 2 p –2 p interaction and indirect 2 p –4 p /4 d –2 p interaction result in a long-range ferromagnetic ground state. With large magnetization energy, room temperature ferromagnetism is expected. Additionally, the Zr-rich condition with NO as N source is suggested to realize the N doping in cubic ZrO 2 .

Charge transport in cobalt-doped iron pyrite

The Hall effect and resistivity of the carrier-doped magnetic semiconductor ${\text{Fe}}_{1\ensuremath{-}x}{\text{Co}}_{x}{\text{S}}_{2}$ were measured for $0\ensuremath{\le}x\ensuremath{\le}0.16$, temperatures between 0.05 and 300 K, and fields of up to 9 T. Our Hall data indicate electron charge carriers with a density of only $10--30\text{ }\mathrm{%}$ of the Co density of our crystals. The charge-carrier transport is dominated by a Kondo-like anomaly below 20 K for $x$ less than that required to form a long-range magnetic state, ${x}_{c}$. For $xg{x}_{c}$, the resistivity and magnetoresistance resemble that of a spin glass with a reduction in the resistivity by as much as 35% in 5 T fields. Although the product of the Fermi wave vector and the mean-free path, ${k}_{F}\ensuremath{\ell}$, varies between 1.5 and 15 over the range of $x$ investigated, we observe no indication of quantum corrections to the resistivity, $\ensuremath{\rho}$, as $\ensuremath{\rho}$ is dominated by the Kondo and spin glasslike anomalies down to very low temperature. Despite the previous identification of magnetic Griffiths phase formation in the magnetic and thermodynamic properties of this system for the same range of $x$, we measure a saturating resistivity below 0.5 K indicating Fermi liquidlike transport. We also observe an enhancement of the residual resistivity ratio by almost a factor of 2 for samples with $x\ensuremath{\sim}{x}_{c}$ indicating temperature-dependent scattering mechanisms beyond simple carrier-phonon scattering. We speculate that this enhancement is due to charge carrier scattering from magnetic fluctuations which contribute to the resistivity over a wide temperature range.

Nanoscale Structural and Chemical Properties of Antipolar Clusters in Sm-Doped BiFeO3 Ferroelectric Epitaxial Thin Films

The local atomic structure and nanoscale chemistry of an antipolar phase in Bi0.9Sm0.1FeO3 epitaxial thin films are examined by an array of transmission electron microscopy (TEM) coupled with electron diffraction and electron energy-loss spectroscopy methods. The observations are tied to macroscopic properties of the films, namely, polarization-electric field hysteresis loops, dielectric constant-electric field hysteresis loops, and the dielectric loss. At room temperature, the local Sm deficiency was determined to destabilize the long-range ferroelectric state, resulting in the formation of local antipolar clusters with the appearance of PbZrO3-like antiparallel cation displacements, which give rise to 1/4{011} and 1/4{211} reflections as well as 1/2{321}, because of in-phase oxygen octahedral tilts. Aberration-corrected TEM analysis reveals that the antipolar structure is actually a lamellar of highly dense ferroelectric domains with alternating polarizations. With increasing temperature, a phase transi...

Strain Effect in Cation Disorder Manganite Films

Y and Sr co-doped La2/3Ca1/3MnO3 films with different A-site cation disorder were deposited on Yttrium-stabilized ZrO2 (YSZ) single crystal substrate by modified off-axis rf magnetron sputtering technology. The influences of A-site cation disorder and biaxial strain on the surface morphologies and transport properties are discussed in detail. At high temperature, the mechanism of conduction is changed from the small polaron hopping model to the variable-range hopping model with increasing cation disorder, which reveals that cation disorder induces carrier localization. The Curie temperature and the magnetoresistance decrease with the increase of cation disorder. It reveals the variation of phase separation to be caused by the increasing cation disorder which suppresses the long-range FM metal state.

10.1007/s11498-008-3013-8

Two types of anisotropic polymer systems were studied in the spherical approximation used in the classical theory of ferromagnetism. These were a three-dimensional system composed of weakly interacting layers with isotropic interactions between chain segments in the layer planes and thin quasi-two-dimensional polymer films possessing intra-and interchain interaction anisotropy, whose behavior is close to that of two-dimensional systems. Laws that govern a change in the temperature T cr of phase transition from the long-range order state to a disordered state depending on the magnitude of anisotropy and the size of the layers were established. For systems of the former type in which interlayer interactions is weakened, T cr tends to zero, being inversely proportional to lng, where g is the ratio of the interaction constant between the layers to that of inplane interaction in a layer. For systems of the latter type, the transition temperature T cr → 0 according to the T cr ∼ √ɛ law, where ɛ is the parameter that characterizes the anisotropy of intra-and interchain interactions. The number of layers required for the systems to be considered three-dimensional was estimated. Regardless of the type of boundary conditions for finite systems, the number of layers increases with enhancement of interaction anisotropy (a decrease in g and ɛ) and an increase in the number of chains in the layers, especially for systems of the former type. Transverse orientational correlations of chain segments with respect to the arrangement of the layers decrease according to a power law, as in the case of infinite two-dimensional systems. There are fluctuations of three-dimensional long-range orientation order in the plane of the layers, the fluctuations are enhanced with an increase in the anisotropy of interactions in the system.

Research on improve the SNR of ultracold cesium molecule rovibronic spectrum via best optimization parameter control

Ultracold atom photoassociation spectroscopy is significant for studying the long-range molecular potential energy structure. The signal-noise ratio of ultracold Cesium Molecule photoassociation Rovibronic Spectrum is one of the indicators as a measure of detection technology which directly affect the distinguishing ability and detection sensitivity of the spectra. We obtain an long-range ultracold cesium molecular hyperfine rovibration spectra by modulating the fluorescence spectroscopy. We find that demodulation parameters have a significant impact to the signal-noise ratio of spectra by studying the demodulation parameters such as integration time and sensitivity, which show nonlinear relation with the ratio. We achieve the optimal control of the signal-noise ratio for spectrum according to our experiment, which laid an important foundation for further studying the long-range state rovibration level of ultracold cesium molecule.

Structural, thermal expansion and heat capacity study of lead-free [(1 − x)(Na0.5Bi0.5)–xBa]Zr1−y Ti y O3 ceramics

Lead-free ceramics of Na0.5Bi0.5TiO3–Ba(Ti,Zr)O3 (NBT–BTZ) were prepared by solid phase hot pressing sintering process. The obtained samples show perovskite structure. Structural, the heat capacity, thermal expansion and pyroelectric measurements were made in wide temperature range. The broad anomalies of heat capacity and thermal expansion were observed, which approximately correspond to structural, pyroelectric and dielectric properties. It was concluded that these anomalies can be connected with temperature features of polar regions and with formation of long-range ferroelectric state. The obtained results are discussed in the framework of foreign ions/lattice imperfections, which create local electric and elastic fields. The NBT–BTZ system is expected to be a new promising candidate for lead-free electronic ceramics.

Degenerate ferrimagnetic ground state of frustrated kagome lattice

The frustrated Ising model on kagome lattice with nearest-neighboring antiferromagnetic interaction is investigated by using Monte Carlo simulation of the Wang–Landau algorithm and Glauber dynamics. The geometrical frustration leads to a particularly high degeneracy of ground states in this system. A small magnetic field applied can lift the degeneracy partially, and produce the magnetization plateau of 1/3 saturate value ( Ms), which is analogous to the magnetic behavior in triangular antiferromagnetic system. However, different from the long-range ferrimagnetic state responsible for 1/3 Ms plateau in triangular lattice, the ferrimagnetic ground state corresponding to 1/3 Ms plateau in kagome lattice is short-ranged and still highly degenerate. Furthermore, the spin configuration of these degenerate ferrimagnetic ground states show an inherent characteristic that the spins along the magnetic field must be aligned on the closed loops, which can be well understood in terms of geometrical frustration.

Multiprobe high-pressure experiments inCePd0.6Rh0.4andCePd3

Abstract Results of recent multiprobe high-pressure experiments on ferromagnetic CePd 0.6 Rh 0.4 and intermediate-valent CePd 3 are presented. Simultaneous resistivity ( ρ ), thermopower (S), and ac heat capacity measurements show that the long-range ferromagnetic state of CePd 0.6 Rh 0.4 vanishes in the proximity of a sharp valence-crossover pressure p V ≈ 7.5 GPa , i.e. before reaching a quantum critical point. However, a magnetic signal that is progressively suppressed is still detected at higher pressures. For CePd 3 , the results of simultaneous ρ ( T , p ) and S ( T , p ) measurements up to 22 GPa and down to the mK temperature range show a surprisingly weak pressure dependence.

Direct Measurement of the Cs2 0u+ (P3/2) High-Lying Vibrational Spectroscopy Using Photon Counting

We report on the photoassociation of cold Cs atoms giving spectroscopy data of the 0 u + long-range molecular state in the asymptotic range of [-6.2, -2.5 cm -1 ] close to the 6S 1/2 +6P 3/2 dissociation limit using photon counting technique. 24 new high-lying vibrational levels of the 0 u + long-range state are identified to lead to the formation of excited molecules in the photoassociation process. Fitting experimental data to improved LeRoy–Bernstein formula, we obtain long-range molecular coefficient with a high precision.

Spectroscopy of 39K85Rb triplet excited states using ultracold a 3Σ+ state molecules formed by photoassociation

Convenient state-selective detection methods are proposed for exploring triplet Rydberg states from the metastable a 3Σ+ state of ultracold KRb molecules by resonance-enhanced two-photon ionization and time-of-flight (TOF) mass spectroscopy. This would allow the first accurate determination of the ionization potential. Particularly suitable resonant intermediate states include the 2 3Π Ω, 3 3Σ+ and 4 3Σ+ states, and we report spectroscopic studies of these states. For the 2 3Π Ω state, the spin–orbit components (Ω = 0+, 0−, 1 and 2) have been investigated and a shallow long-range state (5(0+)) at ∼ 9.3 Å has been observed. We compare our observations of these three states with predictions based on ab initio potential energy curves. Such studies may also permit the direct observation of autoionizing resonances leading to efficient formation of low-lying rovibrational levels of the 2Σ+ ground state of KRb+, ideally in the v+= 0, N+= 0 level.

Study on

Abstract In order to clarify the magnetic nature of a delafossite-type oxide, CuCr 1 - x Mg x O 2 ( x = 0 and 0.03), we have performed zero field (ZF-) and weak transversal field (wTF-) μ + SR measurements in the temperature range between 1.8 and 50 K using polycrystalline samples. The wTF- μ + SR measurements suggested that both samples undergo a magnetic transition at T m = 26 K , clarifying that T m is not altered by the Cr 3 + substitution with Mg 2 + . The ZF- μ + SR measurements indicated the existence of a clear muon-spin precession ( ∼ 50 MHz at T → 0 K ) signal for the x = 0 sample below T m , indicating a long-range antiferromagnetic order state, whereas the absence of long-range order for the x = 0.03 sample even at 1.8 K.

Magnetic-Field Induced Superconductor–Antiferromagnet Transition in Lightly Doped RBa2Cu3O6+x (R = Lu, Y) Crystals

The remarkable sensitivity of the c-axis resistivity and magnetoresistance in cuprates to the spin ordering is used to clarify the doping-induced transformation from an antiferromagnetic (AF) insulator to a superconducting (SC) metal in RBa2Cu3O6+x (R = Lu, Y) single crystals. The established phase diagram demonstrates that the AF and SC regions apparently overlap: The superconductivity in RBa2Cu3O6+x, in contrast to La2−xSrxCuO4, sets in before the long-range AF order is completely destroyed by hole doping. Magnetoresistance measurements of superconducting crystals with low Tc≤15–20 K give a clear view of the magnetic-field induced superconductivity suppression and recovery of the long-range AF state. What still remains to be understood is whether the AF order actually persists in the SC state or just revives when the superconductivity is suppressed, and in the former case, whether the antiferromagnetism and superconductivity reside in nanoscopically separated phases or coexist on an atomic scale.

Effects of lanthanum modification on dielectric properties of Pb(Zr0.90,Ti0.10)O3 ceramics: enhanced antiferroelectric stability

Lanthanum modified lead zirconate titanate ceramics with lanthanum content changing from 2 to 6 at% La and a Zr/Ti ratio of 90/10 (PLZT x/90/10) have been analyzed by using X-ray diffraction, dielectric response, differential scanning calorimetry, and ferroelectric hysteresis. An antiferroelectric state was found to be stabilized, whereas the long-range ferroelectric state was disrupted by lanthanum substitution on the lead sites. A ferroelectric state is shown to be stable over an antiferroelectric state for low lanthanum contents in a wide temperature range, where both phases coexist. With the increase of the lanthanum concentration, the long-range coherency of the ferroelectric state is suppressed, i.e., the temperature range of the ferroelectric state stability decreased, disappearing for x > 3 at% La.

Spin effects in(6s1∕2+6p1∕2)0u+Cs2133weakly bound molecules analyzed by using the Lu-Fano method coupled to the improved LeRoy-Bernstein formula

We present an analysis of spectroscopic data concerning the long-range molecular state $(6{s}_{1∕2}+6{p}_{1∕2}){0}_{u}^{+}$ of $^{133}\mathrm{Cs}_{2}$ [M. Pichler, H. Chen, and W. C. Stwalley, J. Chem. Phys. 121, 1796 (2004)] by using the Lu-Fano method coupled to the improved LeRoy-Bernstein formula. The obtained Lu-Fano graph exhibits the coupling of molecular series to the $(6{s}_{1∕2}+6{p}_{3∕2}){0}_{u}^{+}$ state. The coupling is due to the spin effects in the molecule. A two-channel model involving the improved LeRoy-Bernstein formula allows us to characterize the molecular series, to localize the perturbing levels, to evaluate the coupling in the vicinity of each perturbing level (five observed for Cs) in a two-level approach and in a more accurate multilevel description. Furthermore, we predict the energy and the width of the first predissociated level.