Magneto-resistance and vortex phase diagram of BaNi_(0.1)Fe_(1.9)As_2 single crystal

The transition from vortex glass to a liquid phase is studied in Ba Ni0.1Fe1.9As2 single crystal with Tc = 19.4 K by magneto-resistance measurements. The resistivity curves are measured in magnetic fields in a range of 0 T–13 T for H‖c and H⊥c. Good scalings for all values of resistivity ρ（H, T） and the effective pinning potential U0（H, T） are obtained with the modified vortex glass theory by using the critical exponents s and H0. Phase diagrams for H‖c and H⊥c are determined based on the obtained vortex glass temperature Tg, the vortex dimensionality crossover temperature T＊, and the upper critical magnetic field Hc2. Our results suggest that both below and above 5 T, single vortex pinning co-exists with collective creep, and collective creep is dominant. There is a narrower vortex liquid region for H⊥c than for H‖c in the vortex phase diagram, which may originate from a stronger pinning force.

Establishment of magneto-dielectric effect and magneto-resistance in composite of PLT and Ba-based U-type hexaferrite

We are examining the behavior of a composite made of ferroelectrics with strong dielectric properties and ferrites with magnetic properties due to the rising need for materials for multipurpose devices.Many application avenues will be favored by the pairing of these materials’individual qualities with one another.Perovskite and U-type hexaferrite composite materials have been chosen for this study based on their magnetic and dielectric properties.The composites,(1−x)PLT−x(Ba1−3xNd2x)4Co2Fe36O60 where x=0.52,0.54,0.56,0.58 are prepared by solid state reaction method and phase formation was examined.Consideration has been given to the magnetic,dielectric,and magneto-dielectric properties.This work has established the link between the electric and magnetic domains while applying electric and magnetic forces to the materials.The magneto-dielectric research revealed magneto-electric coupling in all of the samples.However,the sample shows the maximum coupling for x=0.54 with MDR%values of 93.17%,which might be because this sample appears to have a high magneto-resistance(161%).

Enhanced linear magneto-resistance near the Dirac point in topological insulator Bi2(Te1−xSex)3 nanowires

We report the composition and back-gate voltage tuned transport properties of ternary compound Bi2(Te1−xSex)3 nanowires synthesized by chemical vapor deposition(CVD).It is found that the population of bulk carriers can be suppressed effectively with increasing the Se concentration x.In Bi2(Te1−xSex)3 nanowires with x=25%±5%,the ambipolar surface conduction associated with tuning the Fermi energy across the Dirac point of topological surface states is induced by applying a back-gate voltage.Importantly,we find that while the magnetoresistance(MR)follows the weak antilocalization(WAL)behavior when the Fermi level is tuned away from the Dirac point,MR is enhanced in magnitude and turns more linear in the whole magnetic field range(between±9 T)near the Dirac point.The observation of the enhanced linear magneto-resistance(LMR)and crossover from WAL to LMR,near the Dirac point provides a deeper insight into understanding the nature of topological insulator’s surface transport and the relation between these two widely observed magneto-transport phenomena.

Roll angle measurement system based on triaxial magneto-resistive sensor

Aiming at large error when inertial devices measure the roll angle under high overload conditions,the article designs one kind of roll angle measurement system based on magneto-resistive sensor which calculates the roll angle by micro controller STM32.Experiment results of a triaxial turntable show that using magneto-resistive sensor to measure roll angle is feasible and of high accuracy,and it can calculate the roll angle of the conventional projectile with the error in 1°.

Negative Magneto—Resistance Beyond Weak Localization in Three—Dimensional Billiards：Effect of Arnold Diffusion

We investigate a semiclassical conductance for ballistic open three-dimensional (3-d) billiards. For partially or completely broken-ergodic 3-d billiards such as SO(2) symmetric billiards, the dependence of the conductance on the Fermi wavenumber is dramatically changed by the lead orientation. Application of a symmetry-breaking weak magnetic field brings about mixed phase-space structures of 3-d billiards which ensures a novel Arnold diffusion that cannot be seen in 2-d billiards. In contrast to the 2-d case, the anomalous increment of the conductance should inevitably include a contribution arising from Arnold diffusion as well as a weak localization correction. Discussions are devoted to the physical condition for observing this phenomenon.

Investigation of dimensionality in superconducting NbN thin film samples with different thicknesses and NbTiN meander nanowire samples by measuring the upper critical field

We study superconducting properties of NbN thin film samples with different thicknesses and an ultra-thin NbTiN meander nanowire sample.For the ultra-thin samples,we found that the temperature dependence of upper critical field(Hc2)in parallel to surface orientation shows bending curvature close to critical temperature Tc,suggesting a two-dimensional(2D)nature of the samples.The 2D behavior is further supported by the angular dependence measurements of Hc2 for the thinnest samples.The temperature dependence of parallel upper critical field for the thick films could be described by a model based on the anisotropic Ginzburg-Landau theory.Interestingly,the results measured in the field perpendicular to the film surface orientation show a similar bending curvature but in a much narrow temperature region close to Tc for the ultra-thin samples.We suggest that this feature could be due to suppression of pair-breaking caused by local in-homogeneity.We further propose the temperature dependence of perpendicular Hc2 as a measure of uniformity of superconducting ultra-thin films.For the thick samples,we find that Hc2 shows maxima for both parallel and perpendicular orientations.The Hc2 peak for the perpendicular orientation is believed to be due to the columnar structure formed during the growth of the thick films.The presence of columnar structure is confirmed by transmission electron microscopy(TEM).In addition,we have measured the angular dependence of magneto-resistance,and the results are consistent with the Hc2 data.

Defect Detection in CK45 Steel Structures through C-scan Images Using Deep Learning Method

In the present paper,a method for reliable estimation of defect profile in CK45 steel structures is presented using an eddy current testing based measurement system and post-processing system based on deep learning technique.So a deep learning method is used to determine the defect characteristics in metallic structures by magnetic field C-scan images obtained by an anisotropic magneto-resistive sensor.Having designed and adjusting the deep convolution neural network and applied it to C-scan images obtained from the measurement system,the performance of deep learning method proposed is compared with conventional artificial neural network methods such as multilayer perceptron and radial basis function on a number of metallic specimens with different defects.The results confirm the superiority of the proposed method for characterizing defects compared to other classical training-oriented methods。

Optical and electronic properties of single modulation doped GaAs/AlGaAs V-grooved quantum wire modified by ion implantation

Single GaAs/Al0.5Ga0.5As V-grooved quantum wire modified by selective ion-implantation and rapid thermally annealing was investigated by spatially-resolved microphotoluminescence and magneto-resistance measurement. Spatially-resolved photoluminescence results indicate that the ion-implantation induced quantum well intermixing raises significantly the electron subband energies of the side quantum wells and vertical quantum wells, and more efficient accumulation of electrons in the quantum wires is achieved. Furthermore, the polarization properties of the photoluminescence from the quantum wires show large linear polarization degree up to 63%. Magneto- transport investigation on the ion implanted quantum wire samples presents the quasi-one dimensional intrinsic motion of electrons, which is important for the design and optimization of one dimensional electronic devices.