Advances in Condensed Matter Physics The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Amorphization Effect for Kondo Semiconductor CeRu2Al10 Wed, 24 May 2017 07:57:39 +0000 We measured the magnetic susceptibility , electrical resistivity , and specific heat of a sputtered amorphous (a-)CeRu2Al10 alloy. value for a-CeRu2Al10 alloy follows a Curie-Weiss paramagnetic behavior in the high-temperature region, and magnetic transition was not observed down to 2 K. The effective paramagnetic moment is 1.19 /Ce-atom. The resistivity shows a typical disordered alloy behavior, that is, small temperature dependence for the whole temperature range. We observed an enhancement of and in the low-temperature region of  K. The enhancement in is suppressed by applying a magnetic field. It is suggested that this behavior is caused by the Kondo effect. Yusuke Amakai, Yasuhiro Shiojiri, Kei Ishihara, Hiroto Hitotsukabuto, Shigeyuki Murayama, Naoki Momono, and Hideaki Takano Copyright © 2017 Yusuke Amakai et al. All rights reserved. Resonant Scattering and Energy Relaxation in Quantum Dot Systems Thu, 11 May 2017 07:34:11 +0000 We propose a new Auger-like mechanism for energy relaxation in quantum dots (QD) driven by resonant scattering of delocalized wetting layer (WL) carriers. It is demonstrated that resonant scattering leads to a considerable increase in the relaxation rate that can explain experimentally obtained relaxation rates. Analytical results for the relaxation rate are obtained for rectangular dots revealing a weak logarithmic dependence on the dot depth and level density. Comparing results for a rectangular and a parabolic QD model we conclude that the relaxation rate is not very sensitive to a chosen model. I. A. Larkin and A. Vagov Copyright © 2017 I. A. Larkin and A. Vagov. All rights reserved. Characteristic Evaluation of Organic Light-Emitting Diodes Prepared with Stamp Printing Technique Wed, 10 May 2017 08:16:59 +0000 We have reported on a stamp printing technique that uses PET release film as a printing stamp to deposit TPBi thin film served as the electron transport layer of the organic light-emitting diodes. TPBi thin film was printed with a good uniformity and resolution. Effect of deposition conditions on optical and electrical properties and surface roughness of TPBi thin film have been studied under spectroscopy and atomic force microscopy, respectively. It is found that characteristic of TPBi thin film is improved via controlled stamp temperature and time. Since TPBi thin film exhibits the surface morphology comparable to that of conventional spin-coating thin film, our findings suggest that PET release film-based stamp printing approach is possible to use as an alternative deposition of the organic thin film as compared with a traditional one. Apisit Chittawanij and Kitsakorn Locharoenrat Copyright © 2017 Apisit Chittawanij and Kitsakorn Locharoenrat. All rights reserved. Light Polarization Using Ferrofluids and Magnetic Fields Tue, 09 May 2017 00:00:00 +0000 We are presenting an experimental setup based on polarized light, enabling the visualization of the magnetic field of magnetic assemblies using a Hele-Shaw cell filled with ferrofluids. We have simulated the observed patterns with hypergeometric polynomials. Alberto Tufaile, Timm A. Vanderelli, and Adriana Pedrosa Biscaia Tufaile Copyright © 2017 Alberto Tufaile et al. All rights reserved. Stability and Dissipation of Many Components’ Systems and Application to Metamaterials Sun, 30 Apr 2017 13:09:46 +0000 Dykhne’s method, based on rotational symmetry of two-dimensional equations of constant direct current, was applied to study the properties of the medium, consisting of reactances—of inductors and capacitors (nondissipative elements). The exact solution for the 4-component system consisting of the two different types of 2 inductors and 2 capacitors, randomly placed and connected, was obtained. The obtained solution for investigated system has the two features: (1) the finite dissipation in the nondissipative system of inductors and capacitors; (2) appearance of plateau—the constant value of effective conductivity in a wide range of concentrations of components. The obtained results were useful for description of composite metamaterials. Valeriy E. Arkhincheev Copyright © 2017 Valeriy E. Arkhincheev. All rights reserved. Magnetic Properties of Sm-Fe-N/Co-B Composite Magnets Prepared by Chemical Reduction Mon, 24 Apr 2017 00:00:00 +0000 An attempt was made to produce Sm-Fe-N/Co-B composite magnets by chemical reduction. It was found that a composite powder consisting of Sm-Fe-N particles coated with fine Co-B particles could be obtained by chemical reduction. The Sm-Fe-N/Co-B composite powder acted as a single hard magnetic phase and showed a smooth hysteresis loop. The composite powder exhibited a higher remanence of 93.1 Am2/kg and a higher coercivity of 0.45 MA/m than a mixture of the Sm-Fe-N powder and Co-B powder prepared by a similar procedure but using a higher concentration of aqueous solution for the chemical reduction. Tetsuji Saito Copyright © 2017 Tetsuji Saito. All rights reserved. Stability of Bar Code Information Stored in Magnetic Nanowire Arrays Wed, 19 Apr 2017 09:24:12 +0000 Firmware applications such as security codes, magnetic keys, and similar products can be stored in magnetic bar codes similar to optical bar codes. This can be achieved on the triangular lattice present in porous alumina, whose pori can be filled by magnetic material, over which magnetic bar codes can be inscribed. We study the conditions to improve the durability of the stored information by minimizing the repulsive energy among wires with parallel magnetization within the same bar but interacting with attractive energy with wires in the neighboring bar. The following parameters are varied to minimize the energy of the system: relative amount of magnetization orientation within the bar code area in any orientation, width of the bars, and distribution of wider bars to the outside or to the inside of the code. It is found that durability of the code is favored for equal amount of magnetization in each direction, abundance of narrow bars trying to locate a few wider ones towards the center. Three real commercial optical bar codes taken at random were mapped into magnetic bar codes; it is found that the corresponding magnetic energies are similar to those analyzed here which provides a realistic test for this approach. Eduardo Cisternas, Eugenio E. Vogel, and Julián Faúndez Copyright © 2017 Eduardo Cisternas et al. All rights reserved. Intrinsic and Extrinsic Ferromagnetism in Co-Doped Indium Tin Oxide Revealed Using X-Ray Magnetic Circular Dichroism Thu, 13 Apr 2017 06:44:35 +0000 The effects of high-temperature annealing on ferromagnetic Co-doped Indium Tin Oxide (ITO) thin films have been investigated using X-ray diffraction (XRD), magnetometry, and X-Ray Magnetic Circular Dichroism (XMCD). Following annealing, the magnetometry results indicate the formation of Co clusters with a significant increase in the saturation magnetization of the thin films arising from defects introduced during cluster formation. However, sum rule analysis of the element-specific XMCD results shows that the magnetic moment at the Co sites is reduced after annealing. The effects of annealing demonstrate that the ferromagnetism observed in the as-deposited Co-doped ITO films arises from intrinsic defects and cannot be related to the segregation of metallic Co clusters. A. M. H. R. Hakimi, F. Schoofs, M. G. Blamire, S. Langridge, and S. S. Dhesi Copyright © 2017 A. M. H. R. Hakimi et al. All rights reserved. The Tunnelling Current through Oscillating Resonance and the Sisyphus Effect Tue, 11 Apr 2017 00:00:00 +0000 The tunnelling current through an oscillating resonance level is thoroughly investigated exactly numerically and with several approximations—analytically. It is shown that while the oscillations can increase the tunnelling current (and in several cases the increase is exponentially large), their main effect is to reduce it dramatically at certain energies. In fact, the current in the presence of the oscillations cannot increase the maximum current of the adiabatic solution. That is why, while the elevator effect does occur in this system, the Sisyphus effect is the more dominant and prominent one. Er’el Granot Copyright © 2017 Er’el Granot. All rights reserved. Study of Low Voltage Prebreakdown Sites in Multicrystalline Si Based Cells by the LBIC, EL, and EDS Methods Mon, 10 Apr 2017 00:00:00 +0000 Breakdown sites in multicrystalline Si solar cells have been studied by reverse-bias electroluminescence, electron beam induced current (EBIC) and laser beam induced current (LBIC), and Energy Dispersive X-Ray Spectroscopy methods. In the breakdown sites revealed by EL at small reverse bias (~5 V), the enhanced aluminum and oxygen concentration is revealed. Such breakdowns can be located inside the depletion region because they are not revealed by the EBIC or LBIC methods. Breakdowns revealed by EL at larger bias correlate well with extended defects in the EBIC and LBIC images. V. I. Orlov, E. B. Yakimov, E. P. Magomedbekov, and A. B. Danilin Copyright © 2017 V. I. Orlov et al. All rights reserved. Design and Fabrication of a Novel Wideband DNG Metamaterial with the Absorber Application in Microwave X-Band Sun, 26 Mar 2017 00:00:00 +0000 A novel metamaterial, which exhibits a wideband double negative behavior in X-band, is proposed, designed, and investigated in this paper. The metamaterial is composed of modified S-shaped split-ring resonators (S-SRR). The periodic structure is designed and simulated using CST MWs. Next, the experiments are carried out, and it is shown that the simulation and the experimental results agree well and the designed structure has a wide bandwidth in X-band. An absorber application of this metamaterial is also provided, and the structure can be used as an absorber with absorption rate of over 80% for the polarization angles between 0° and 40°. Ahmed Mahmood, Gölge Ögücü Yetkin, and Cumali Sabah Copyright © 2017 Ahmed Mahmood et al. All rights reserved. Influence of Pressure on the Temperature Dependence of Quantum Oscillation Phenomena in Semiconductors Mon, 20 Mar 2017 00:00:00 +0000 The influence of pressure on the oscillations of Shubnikov-de Haas (ShdH) and de Haas-van Alphen (dHvA) in semiconductors is studied. Working formula for the calculation of the influence of hydrostatic pressure on the Landau levels of electrons is obtained. The temperature dependence of quantum oscillations for different pressures is determined. The calculation results are compared with experimental data. It is shown that the effect of pressure on the band gap is manifested to oscillations and ShdH and dHvA effects in semiconductors. G. Gulyamov, U. I. Erkaboev, and A. G. Gulyamov Copyright © 2017 G. Gulyamov et al. All rights reserved. Geometrically Tunable Transverse Electric Field in Multilayered Structures Wed, 15 Mar 2017 06:34:27 +0000 Appearance of a transverse component in dc electric field with respect to the applied current is investigated in periodic multilayer composite structures made of nanometer-to-micrometer scale alternating layers of two different homogeneous and isotropic conducting materials. Dependence of the transverse electric field on geometrical orientation of the layers is examined using the coordinate transformation approach. Electric field bending angle as a function of the layers’ resistivity ratio is studied in detail. It is shown that both the direction and the magnitude of the field can be changed using orientation angle of the layers as a tuning parameter. Roland H. Tarkhanyan and Dimitris G. Niarchos Copyright © 2017 Roland H. Tarkhanyan and Dimitris G. Niarchos. All rights reserved. Corrigendum to “Impact of Pressure and Brine Salinity on Capillary Pressure-Water Saturation Relations in Geological CO2 Sequestration” Tue, 14 Mar 2017 00:00:00 +0000 Jongwon Jung and Jong Wan Hu Copyright © 2017 Jongwon Jung and Jong Wan Hu. All rights reserved. Lattice Dynamics and Transport Properties of Multiferroic DyMn2O5 Tue, 07 Mar 2017 00:00:00 +0000 We have investigated the optical and electrical properties of polycrystalline DyM synthesized by sol-gel method. Analysis of the reflectivity spectrum has led to the observation of 18 infrared (IR) active phonon modes out of 36 predicted ones. We discuss the results in terms of different phonon bands originated as a result of atomic vibrations. Moreover, the optical energy band gap of  eV has been estimated from optical conductivity spectrum. The energy band gap and optical transitions were also determined from UV-visible absorption spectrum and band gap of  eV was estimated. Moreover, DC electrical resistivity shows the p-type polaronic conduction above room temperature. Javed Ahmad, Syed Hamad Bukhari, M. Tufiq Jamil, Mehr Khalid Rehmani, Hammad Ahmad, and Tahir Sultan Copyright © 2017 Javed Ahmad et al. All rights reserved. Spin Transport and Magnetism in Low-Dimensional Materials Tue, 28 Feb 2017 14:45:16 +0000 Xiaohong Xu, Jingsheng Chen, Gillian A. Gehring, Xiangshui Miao, and Hao Zeng Copyright © 2017 Xiaohong Xu et al. All rights reserved. Wideband Negative Permittivity and Double Negative Fishnet-Mushroom-Like Metamaterial in X-Band Waveguide Tue, 28 Feb 2017 09:40:51 +0000 A Fishnet-Mushroom-like metamaterial electromagnetic behaviour is represented in -parameters numerically and experimentally for X-band frequencies arena. The design has introduced a dielectric substrate as a host with metallic parts. The proposed design is predicted to provide the electromagnetic band gap characterization with desired reiterative characteristic parameters, negative permittivity, and negative permeability exhibiting a double negative left-handed region, which is identified with the X-band regime with good agreement between the simulated and the measured results. Ahmed Mahmood, Golge Ogucu Yetkin, and Cumali Sabah Copyright © 2017 Ahmed Mahmood et al. All rights reserved. Experimental Study on Ferromagnetic Shunt Effects on the Critical Current of BSCCO Tape in Stacked Conductors Mon, 27 Feb 2017 08:41:55 +0000 In the 200 m high temperature superconducting (HTS) cable test facility at Chubu University constructed in 2010, a three-layer structure of the tapes in the cable is employed for obtaining the high current capacity up to 2 kA. Previous study shows that the critical current is affected by the layout of the tapes such as gaps and the current feeding mode. In the stacked tape conductors, the critical current of BSCCO tapes shows strong dependence on the current feeding directions between the tapes. The critical current is improved when the opposite-direction current is applied to them and degraded for the same-direction current feeding mode because of strong magnetic field interaction between them from the transport current in each tape. This paper presents the measurements of the critical currents of a BSCCO tape in the stacked conductors with the ferromagnetic materials. By using the ferromagnetic materials surrounding the tapes, self-field of HTS tapes is affected and their critical currents are improved by more than 10%. Ferromagnetic shunt effects on the critical current of HTS tape are reported through the magnetic field analysis. J. Sun, H. Ohara, and S. Yamaguchi Copyright © 2017 J. Sun et al. All rights reserved. Magnetoresistance Effect in NiFe/BP/NiFe Vertical Spin Valve Devices Sun, 26 Feb 2017 06:18:13 +0000 Two-dimensional (2D) layered materials such as graphene and transition metal dichalcogenides are emerging candidates for spintronic applications. Here, we report magnetoresistance (MR) properties of a black phosphorus (BP) spin valve devices consisting of thin BP flakes contacted by NiFe ferromagnetic (FM) electrodes. The spin valve effect has been observed from room temperature to 4 K, with MR magnitudes of 0.57% at 4 K and 0.23% at 300 K. In addition, the spin valve resistance is found to decrease monotonically as temperature is decreased, indicating that the BP thin film works as a conductive interlayer between the NiFe electrodes. Leilei Xu, Jiafeng Feng, Kangkang Zhao, Weiming Lv, Xiufeng Han, Zhongyuan Liu, Xiaohong Xu, He Huang, and Zhongming Zeng Copyright © 2017 Leilei Xu et al. All rights reserved. Low Temperature Conductivity in -Type Noncompensated Silicon below Insulator-Metal Transition Tue, 14 Feb 2017 06:09:42 +0000 We investigate the transport properties of -type noncompensated silicon below the insulator-metal transition by measuring the electrical and magnetoresistances as a function of temperature for the interval 2–300 K. Experimental data are analyzed taking into account possible simple activation and hopping mechanisms of the conductivity in the presence of two impurity bands, the upper and lower Hubbard bands (UHB and LHB, resp.). We demonstrate that the charge transport develops with decreasing temperature from the band edge activation (110–300 K) to the simple activation with much less energy associated with the activation motion in the UHB (28–90 K). Then, the Mott-type variable range hopping (VRH) with spin dependent hops occurs (5–20 K). Finally, the VRH in the presence of the hard gap (HG) between LHB and UHB (2–4 K) takes place. We propose the empiric expression for the low density of states which involves both the UHB and LHB and takes into account the crossover from the HG regime to the Mott-type VRH with increasing temperature. This allows us to fit the low experimental data with high accuracy. A. L. Danilyuk, A. G. Trafimenko, A. K. Fedotov, I. A. Svito, and S. L. Prischepa Copyright © 2017 A. L. Danilyuk et al. All rights reserved. Mesoporous SnO2 Nanowires: Synthesis and Ethanol Sensing Properties Tue, 14 Feb 2017 00:00:00 +0000 The mesoporous SnO2 nanowires composed of nanoparticles and nanopores have been successfully synthesized within the nanochannels of anodic alumina oxide templates by a facile sol-gel method. XRD, SEM, and HRTEM were used to characterize the synthesized mesoporous SnO2 nanowires. The sensing property of the mesoporous SnO2 nanowires in ethanol detection also has been studied. The as-prepared product displays excellent the high sensitivity, rapid response, and excellent repeatability to ethanol. The detection limit of the mesoporous SnO2 nanowires to ethanol reaches 1 ppm. The sensing mechanism of the mesoporous SnO2 nanowires has been further discussed. It is expected that the mesoporous SnO2 nanowires might become a good sensing material for promising industrial applications. Shan-Hong Li, Fang-Fang Meng, Zhong Chu, Tao Luo, Fu-Min Peng, and Zhen Jin Copyright © 2017 Shan-Hong Li et al. All rights reserved. Snowflake-Shaped ZnO Nanostructures-Based Gas Sensor for Sensitive Detection of Volatile Organic Compounds Tue, 07 Feb 2017 00:00:00 +0000 Volatile organic compounds (VOCs) have been considered severe risks to human health. Gas sensors for the sensitive detection of VOCs are highly required. However, the preparation of gas-sensing materials with a high gas diffusion performance remains a great challenge. Here, through a simple hydrothermal method accompanied with a subsequent thermal treatment, a special porous snowflake-shaped ZnO nanostructure was presented for sensitive detection of VOCs including diethyl ether, methylbenzene, and ethanol. The fabricated gas sensors exhibit a good sensing performance including high responses to VOCs and a short response/recovery time. The responses of the ZnO-based gas sensor to 100 ppm ethanol, methylbenzene, and diethyl ether are about 27, 21, and 11, respectively, while the response times to diethyl ether and methylbenzene are less than 10 seconds. The gas adsorption-desorption kinetics is also investigated, which shows that the gas-sensing behaviors to different target gases are remarkably different, making it possible for target recognition in practical applications. Tianli Han, Xuexue Li, Xiaoman Zhang, Jinyun Liu, and Jinjin Li Copyright © 2017 Tianli Han et al. All rights reserved. Microstructure and Magnetic Properties of NdFeB Films through Nd Surface Diffusion Process Wed, 18 Jan 2017 00:00:00 +0000 Ta/Nd/NdFeB/Nd/Ta films were deposited by magnetron sputtering on Si (100) substrates and subsequently annealed for 30 min at 923 K in vacuum. It was found that the microstructure and magnetic properties of Ta/Nd/NdFeB/Nd/Ta films strongly depend on the NdFeB layer thickness. With NdFeB layer thickness increasing, both the grain size and the strain firstly reduce and then increase. When NdFeB layer thickness is 750 nm, the strain reaches the minimum value. Meanwhile, both the in-plane and perpendicular coercivities firstly drastically increase and then slowly decrease with NdFeB layer thickness increasing. The highest in-plane and perpendicular coercivities can be obtained at NdFeB layer thickness of 750 nm, which are 21.2 kOe and 19.5 kOe, respectively. In addition, the high remanence ratio (remanent magnetization/saturation magnetization) of 0.87 can also be achieved in Ta/Nd/NdFeB (750 nm)/Nd/Ta film. Wenfeng Liu, Mingang Zhang, Kewei Zhang, and Yuesheng Chai Copyright © 2017 Wenfeng Liu et al. All rights reserved. An Improved Theoretical Approach to Study Electromagnetic Waves through Fiber Bragg Gratings Tue, 10 Jan 2017 00:00:00 +0000 We show that using the theory of finite periodic systems we obtain an improved approach to calculate transmission coefficients and transmission times of electromagnetic waves propagating through fiber Bragg gratings. We discuss similarities, advantages, and differences between this approach and the well known less accurate one coupled mode approximation and the pseudo-Floquet Mathieu functions approach. Pedro Pereyra Copyright © 2017 Pedro Pereyra. All rights reserved. Magnetothermopower in A2−xLaxFeMoO6 (A = Sr, Ba) Thu, 05 Jan 2017 11:03:28 +0000 A magnetothermopower has been observed in electronically spin-polarized polycrystalline and Ba2FeMoO6. The magnetothermopower is linear up to ~50 K for and linear up to ~270 K for Ba2FeMoO6. We suggest that the magnetothermopower may arise from a spin-tunneling magnetothermopower between the grains. G. V. M. Williams and J. Stephen Copyright © 2017 G. V. M. Williams and J. Stephen. All rights reserved. Profile of a Faceted Macrostep Caused by Anomalous Surface Tension Thu, 05 Jan 2017 09:42:48 +0000 The height profile of a macrostep on a vicinal surface near equilibrium is studied numerically using a restricted solid-on-solid model with a point-contact-type step-step attraction (p-RSOS model). We calculate the surface tension of vicinal surfaces around the (001) surface inclined towards the direction using the density-matrix-renormalization group method. We also calculate the height profiles of vicinal surfaces using the Monte Carlo method and study the connection between the height profile of the macrostep near equilibrium and the discontinuous surface tension. We find that the height profile of a macrostep on a vicinal surface near equilibrium can be classified depending on the zone in the faceting diagram where the system exists. We also find finite size effects both for the height profile and for the inhibition of the macrostep motion in the relaxation process to the equilibrium state. Noriko Akutsu Copyright © 2017 Noriko Akutsu. All rights reserved. Vibrational Spectroscopy of Binary Titanium Borides: First-Principles and Experimental Studies Tue, 03 Jan 2017 12:08:22 +0000 Vibrational dynamics of binary titanium borides is studied from first-principles. Polarized and unpolarized Raman spectra of TiB, TiB2, and Ti3B4 are reported along with the experimental spectra of commercial powder and bulk TiB2 containing less than 1 wt.% of impurity phases. The X-ray diffraction spectroscopy, applied for phase composition examination of both bulk and powder materials, identifies only the TiB2 phase. The simulated Raman spectra together with literature data support interpretation and refinement of experimental spectra which reveal components arising from titanium dioxide (TiO2) and amorphous boron carbide (B4C) impurity phases as well as graphitic carbon. These contaminations are the by-products of synthesis, consolidation, and sintering aids employed to fabricate powder and bulk titanium diboride. Urszula D. Wdowik, Agnieszka Twardowska, and Bogusław Rajchel Copyright © 2017 Urszula D. Wdowik et al. All rights reserved. Antimicrobial Efficacy and Cell Adhesion Inhibition of In Situ Synthesized ZnO Nanoparticles/Polyvinyl Alcohol Nanofibrous Membranes Sun, 25 Dec 2016 14:22:32 +0000 Nanoparticle metal oxides are emerging as a new class of important materials in medical, agricultural, and industrial applications. In this context, free zinc oxide (ZnO) nanoparticles (NPs) have been increasingly shown with broad antimicrobial activities. However, biological properties of immobilized ZnO NPs on matrixes like nanofibrous membranes are still limited. In this study, in situ synthesized ZnO NPs/polyvinyl alcohol (PVA) nanofibrous membranes were fabricated by electrospinning with different zinc acetate concentrations. Characterization results indicated that, with 5 mM zinc acetate, uniform size ZnO NPs (~40 nm) were formed and evenly distributed on the membrane surface. The surfaces became more hydrophobic with higher concentration of zinc acetate. ZnO NPs/PVA nanofibrous membranes showed a broad spectrum of antimicrobial activities and cell adhesion inhibiting effects against four microorganisms including Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli, fungi Candida albicans, and spores of Aspergillus niger. Our data revealed that the major antimicrobial mechanism could be attributed to cell membrane damage and cellular internalization of ZnO NPs, while the hydrophobic surface of the membrane primarily contributed to the cell adhesion inhibition. This study suggests that ZnO NPs/PVA nanofibrous membranes could potentially be used as an effective antimicrobial agent to maintain agricultural and food safety. Jian Li, Qun Zhang, Minjing Xu, Changzhu Wu, and Ping Li Copyright © 2016 Jian Li et al. All rights reserved. Generation of Basis Vectors for Magnetic Structures and Displacement Modes Wed, 14 Dec 2016 09:19:40 +0000 Increasing attention is being focused on the use of symmetry-adapted functions to describe magnetic structures, structural distortions, and incommensurate crystallography. Though the calculation of such functions is well developed, significant difficulties can arise such as the generation of too many or too few basis functions to minimally span the linear vector space. We present an elegant solution to these difficulties using the concept of basis sets and discuss previous work in this area using this concept. Further, we highlight the significance of unitary irreducible representations in this method and provide the first validation that the irreducible representations of the crystallographic space groups tabulated by Kovalev are unitary. Z. L. Davies and A. S. Wills Copyright © 2016 Z. L. Davies and A. S. Wills. All rights reserved. Perpendicular Giant Magnetoresistance and Magnetic Properties of Co/Cu Nanowire Arrays Affected by Period Number and Copper Layer Thickness Tue, 13 Dec 2016 08:32:55 +0000 One-dimensional magnetic nanowires have attracted much attention in the last decades due to their unique physical properties and potential applications in magnetic recording and spintronics. In this work, ordered arrays of Co/Cu multilayered nanowires which can be exploited to develop magnetoresistive sensors were successfully prepared using porous anodic alumina (PAA) templates. The structure and morphology of the multilayered nanowire arrays were characterized by transmission electron microscopy and scanning electron microscopy. The nanowire arrays are highly ordered and the average diameter is about 50 nm, which is controlled by the pore diameter of the PAA templates. The influences of period number and Cu layer thickness on the magnetic and the giant magnetoresistance (GMR) properties were investigated. The coercivity and remanence ratio increase first and then gradually tend to be stable with the increase of period number and the Cu layer thickness, while the GMR ratio increases first and then decreases with the increase of the period number accompanied by an oscillatory behavior of GMR as the Cu layer thickness changes, which are ascribed to the spin dependence electron scattering in the multilayers. The optimum GMR of −13% appears at Co (50 nm)/Cu (5 nm) with 200 deposition cycles in our experimental conditions. Juan Han, Xiufang Qin, Zhiyong Quan, Lanfang Wang, and Xiaohong Xu Copyright © 2016 Juan Han et al. All rights reserved.