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The versatility of the template-assisted electrodeposition technique to fabricate complex three-dimensional networks made of interconnected nanowires allows one to easily stack ferromagnetic and non-magnetic metallic layers along the nanowire axis. This leads to the fabrication of unique multilayered nanowire network films showing giant magnetoresistance effect in the current-perpendicular-to-plane configuration that can be reliably measured along the macroscopic in-plane direction of the films. Moreover, the system also enables reliable measurements of the analogous magneto-thermoelectric properties of the multilayered nanowire networks. Here, three-dimensional interconnected NixFe1−x/Cu multilayered nanowire networks (with 0.60≤x≤0.97) are fabricated and characterized, leading to large magnetoresistance and magneto-thermopower ratios up to 17% and −25% in Ni80Fe20/Cu, respectively. A strong contrast is observed between the amplitudes of magnetoresistance and magneto-thermoelectric effects depending on the Ni content of the NiFe alloys. In particular, for the highest Ni concentrations, a strong increase in the magneto-thermoelectric effect is observed, more than a factor of 7 larger than the magnetoresistive effect for Ni97Fe3/Cu multilayers. This sharp increase is mainly due to an increase in the spin-dependent Seebeck coefficient from −7 V/K for the Ni60Fe40/Cu and Ni70Fe30/Cu nanowire arrays to −21 V/K for the Ni97Fe3/Cu nanowire array. The enhancement of the magneto-thermoelectric effect for multilayered nanowire networks based on dilute Ni alloys is promising for obtaining a flexible magnetic switch for thermoelectric generation for potential applications in heat management or logic devices using thermal energy.

Tin‐based nanowire electrodes present desirable properties as lithium‐ion battery anodes, because they undergo volume changes without pulverization. However, they suffer from limited mass loading and propensity for surface parasitic reactions. Herein, we evaluate the electrochemical performances of interconnected nickel‐tin nanowire network electrodes (NiSn 3DNWN) with nanowire diameters of 40 nm, 105 nm, and 230 nm, respectively, that attain mass loadings of up to 3 mg cm‐2. To mitigate the surface parasitic reactions, the effects of fluoroethylene carbonate (FEC) and vinylene carbonate (VC) additives are investigated as a function of nanowire diameter and additive concentration. The results show that FEC and VC of all compositions improve the capacity retentions and coulombic efficiencies of the NiSn 3DNWN electrodes. In 10 vol% FEC, the electrodes demonstrate a similar capacity of ∽ 550 mAh g‐1, but the capacity retentions after 100 cycles are 73.68%, 53.79%, 51.70% for the 40 nm, 105 nm, and 230 nm NiSn 3DNWN, respectively. However, the 105 nm‐diameter nanowire electrode has the highest average coulombic efficiency of 96.55%. Electrochemical impedance spectroscopy and post‐cycling investigations reveal that FEC has the most profound effect on the interphasial resistances, which is reflected in the rate performances of the tested electrodes. This article is protected by copyright. All rights reserved.

Large-scale, electrically interconnected three-dimensional (3-D) Ni crossed nanotube networks have been fabricated using an electrochemical dealloying method within the crossed nanopores of polymer host membranes. This method paves the way for the easy and cost-effective fabrication of 3-D magnetic NT networks with precise spatial arrangement and diameter and wall thickness of 10–100 nm controlled individually. The excellent control over geometrical parameters and morphological features of the Ni crossed nanotube networks leads to tunable magnetic and magneto-transport properties. Particularly, the low field magneto-transport behavior is consistent with the expected vortex-like states formed in different segments of the nanotube scaffold, whereas nucleation of domain walls at the intersection of the nanowire segments play a dominant role in the solid crossed nanowire networks counterpart. The present 3-D networks of nanomagnets are of special interest due to their potential for memory devices, computing architectures, sensing and biomedical applications.

Magnetoresistance and thermopower of crossed NiCr and CoCr nanowire networks have been measured as a function of temperature and chromium content in dilute alloys. At low temperatures, it is found that the impurity effect leads to negative anisotropic magnetoresistance, an observation that even persists until room temperature in diluted CoCr alloy nanowires. The addition of a small amount of Cr in nickel nanowires also abruptly reverses the sign of the thermopower from −20 μV/K for pure Ni up to +18 μV/K for the dilute alloys, implying the switching from n- to p-type conduction. These results are consistent with pronounced changes in the density of states for the majority spin electrons. The high room-temperature power factors of these magnetic nanowire networks (in the range of 1–10 mW/K2 m) provide interesting perspectives for designing n- and p-type legs for flexible spin thermoelectric devices.

There is a proliferation of autonomous microscale devices, which are increasingly in need of power sources of commensurate form factors. The trade-off between the areal energy and power capabilities of miniature energy storage devices restrict their abilities to meet the requirements of these microscale devices. However, three-dimensional (3D) micro- and nanoarchitectures have the potential to meet the energy requirements of autonomous microscale devices, while retaining the power capabilities of thin-film systems. In this paper, we present a novel full-cell architecture and fabrication strategy for 3D microscale energy storage devices based on template-assisted electrodeposition of three-dimensionally interconnected metallic nanowire network, and its subsequent laser-patterning to form interdigitated nanostructured electrodes. The patterned nanowire networks are functionalized with the polyaniline active electrode material via an electroless deposition procedure. We show that a footprint areal capacitance/energy enhancement of more than 5 times is achieved by just 10 μm-high nanowire networks, in addition to enhanced power capabilities.

We developed a versatile template-based fabrication method for growing large arrays of three-dimensionally interconnected polypyrrole nanotubes (or nanowires) with easily tunable geometrical dimensions and spatial arrangement. Such a macroscopic network made up of conducting polymer elongated nanostructures provides an extremely large active surface with increased electrical connectivity, as well as an enhanced structural integrity of the flexible network. The three-dimensional array of polypyrrole nanofibers exhibited an excellent sensitivity towards gaseous ammonia, providing reliable and accurate detection at gas concentrations as low as 1 ppm. The novel preparation approach offers a cost-effective alternative for large-scale production of easily integrable chemiresistive sensors for different applications.

We report the facile and low-cost preparation as well as detailed characterization of dense arrays of passivated ferromagnetic nickel (Ni) nanotubes (NTs) vertically-supported onto solid Au-coated Si substrates. The proposed fabrication method relies on electrochemical synthesis within the nanopores of a supported anodic aluminum oxide (AAO) template and allows for fine tuning of the NTs ferromagnetic walls just by changing the cathodic reduction potential during the nanostructures&rsquo, electrochemical growth. Subsequently, the experimental platform allowed further passivation of the Ni NTs with the formation of ultra-thin antiferromagnetic layers of nickel oxide (NiO). Using adequately adapted magnetic measurements, we afterwards demonstrated that the thickness of the NT walls and of the thin antiferromagneticNiO layer, strongly influences the magnetic behavior of the dense array of exchange-coupled Ni/NiO NTs. The specific magnetic properties of these hybrid ferromagnetic/antiferromagnetic nanosystems were then correlated with the morpho-structural and geometrical parameters of the NTs, as well as ultimately strengthened by additionally-implemented micromagnetic simulations. The effect of the unidirectional anisotropy strongly amplified by the cylindrical geometry of the ferromagnetic/antiferromagnetic interfaces has been investigated with the magnetic field applied both parallel and perpendicular to the NTs axis.

The effects of the deposition potential on the structural and magnetic properties of Ni nanowires with a diameter of 40 nm and lengths varying from 16 up to 56 μm have been studied. The results show that very long NWs exhibit a large enhancement of their uniaxial magnetic anisotropy. This anisotropy reaches values as high as 1.6 × 10 6 erg/cm3 that is comparable with the value due to the magnetostatic anisotropy contribution ( ≈ 5 × 10 6 erg/cm3) and as shown from the results this large anisotropy is practically insensitive to the deposition potential. Moreover, as shown on shorter NWs, this enhancement of the anisotropy is not observed and interestingly the potential does induce structural changes that relate to their magnetic properties. The enhanced anisotropy observed in long NWs is a robust effect as it is independent of the potential, making this property attractive for applications where high uniaxial anisotropies are required.

We reported an efficient way of preparing large and dense ferromagnetic arrays of vertically-aligned Ni nanotubes (NTs). The synthesis method allowed then for a direct, effective and controllable thermal conversion of the as-prepared Ni NTs into heterostructured Ni/NiO NTs, without compromising the nanostructures' verticality to the substrate and their initial tubular integrity. Next, we demonstrated the ability to tune the dipolar interaction field (DIF) in this array of one-dimensional (1D) Ni/NiO heterostructures, just by slightly changing the thickness of the antiferromagnetic NiO layer. Furthermore, the proposed fabrication method assures full compatibility with the standard Si processing, providing thus a direct pathway towards large-scale integrability and manufacturing of a new generation of magnetic devices relying on dense arrays of vertical 1D magnetic nanostructures.

tIn this work, large and dense arrays of zinc oxide (ZnO) nanorods (NRs) were fabricated by an improvedtemplate-free electrodeposition (ECD) route on top of home-made Al-doped ZnO (AZO) thin filmsdeposited on glass. The AZO layer, acting as transparent conducting oxide, was found to display enhancedelectrical and morphological properties compared to other commercially available substrates, facilitat-ing the subsequent electrochemical growth of the ZnO nanostructures. In addition, its intrinsic columnarnature strengthened the vertical orientation of the obtained ZnO NRs. The one-step low-temperatureelectrochemical method did not require any additional seeding layer, being suitable for applications inwhich the process simplicity and substrate’s thermal toughness are essential requirements. The ECDprotocol was optimized as a function of the process temperature and duration, demonstrating the pos-sibility to yield reasonable aspect-ratio ZnO NRs in a relatively short time synthesis. Further structuralstudies confirmed the excellent orientation along c-axis of the ZnO Wurtzite phase and have shown apolycrystalline nature of the NRs, with a well-defined hexagonal symmetry of the crystallites.

The first crystal structures of a dinuclear iron(II) complex with three N1,N2-1,2,4-triazole bridges in the high-spin and low-spin states are reported. Its sharp spin transition, which was probed using X-ray, calorimetric, magnetic, and (57)Fe Mossbauer analyses, is also delineated in the crystalline state by variable-temperature fluorimetry for the first time.

In this article, we show how the microwave properties of ferromagnetic nanowires electrodeposited into a porous polymer template depend on various parameters such as the geometrical parameters of the nanowires array and elaboration conditions. Our nanowires behave as strong uniaxial nanomagnets and exhibit zero-field resonance frequencies tunable up to 36 GHz. Novel microwave devices such as circulators and filters, using a porous polymer template loaded with metallic nanowires, are discussed. An accurate knowledge of magnetic and dielectric properties of the loaded polymer template is mandatory for the design of such devices. (C) 2008 Elsevier B.V. All rights reserved.

Arrays of electrodeposited Co0.96Cu0.04/Cu nanowires into porous polycarbonate membranes have been characterized by ferromagnetic resonance measurements in order to study the effect of the dipolar interactions on the effective anisotropy field as a function of the magnetic and non magnetic layer thickness. It is found that breaking the infinite cylinder geometry reduces their shape anisotropy field, which can be modified to a large extent from 6.5 kOe for non layered nanowires down to nearly zero for layered nanowires with the thinnest magnetic layers. An analytical model is proposed to describe the magnetostatic interactions between magnetic layers and their effect on the total anisotropy field which shows a good agreement with the experiment.

A simple characterization method of the ordering of the nanopores is described for nanoporous anodized aluminium oxides. The method starts with image analysis on scanning electron microscopy representations for the purpose to find repetitive shapes and their centres, i.e. nanopores. Then triangles defined by coordinates of the centres are identified by Delaunay tessellation. Evaluation of the ordering degrees is then performed by a two-level analysis of the triangles. We define order parameters for triangular and hexagonal organization levels and show through typical examples that they are highly sensitive on ordering. (c) 2007 Elsevier B.V. All rights reserved.

Being the exponent of the so-called "bottom-up" approach, self-assembled structures are now-a-days attracting a lot of attention in the fields of science and technology. In this work, we show that nanoscale self-assembled arrays used as templates can provide periodic modulation in superconducting thin films by studying their vortex pinning properties. In this work advantage was made of the fact that self-organized assemblies of identical units such as colloidal crystals and anodic aluminum oxide provide extended periodic topographic surfaces. By directly growing Nb on top of these self-assembled arrays, the templating effect was exploited in order to achieve triangular and honeycomb arrays of pinning centers in thin superconducting films. We show experimentally that periodic matching is achieved in both systems at magnetic fields, well above those present in lithographically prepared pinning arrays (up to 1 T!). Furthermore, we demonstrate in the case of anodic aluminum oxide that the presence of porous antidots in Nb not only provides strongly increased critical currents but also conserves matching at temperatures well below the critical temperature. The studies conducted on these systems indicate that the method of template growth might be considered as a viable alternative for the incorporation of periodic pinning arrays in superconducting applications of today and the future. (c) 2008 Elsevier B.V. All rights reserved.

A simple technique for fabricating single nanowires with well-defined position is presented. The process implies the use of a silicon nitride mask for selective electrochemical growth of the nanowires in a porous alumina template. We show that this method allows the realization of complex nanowire patterns as well as arrays of single nanowires with a precise position and spacing.

We present a study of magnetization and transport properties of superconducting Nb thin films deposited on nanoporous aluminium oxide templates. Periodic oscillations in the critical temperature vs. field, matching effects in fields up to 700 mT and strongly enhanced critical currents were observed. These fields are considerably higher than those typical for periodic pinning arrays made by lithographic techniques, which reflects the benefits of nanostructuring superconductors by using self-organized growth. This method provides a periodic pinning potential with sub-100 nm spacing between the pinning centers, which enhances vortex pinning in broad field and temperature ranges.

A highly ordered hexagonally close-packed nanochannels array was prepared using the self-ordering phenomena during a two-step anodization process of a high purity aluminium foil. The anodized aluminium oxide, with pore diameters of about 280 nm and interpore distances of about 450 nm was prepared as a suspended membrane of about 15 mu m thickness on the aluminium frame to which it belongs. The Al2O3 capillaries were bombarded with 3 keV Ne6+ ions. The first results unambiguously show the existence of ion guiding observed at 5 degrees and 7.5 degrees tilt angles of the capillaries compared to the beam direction. To the best of our knowledge, such ion guiding effects of slow ions through hexagonally ordered nanochannels in alumina has not been reported previously.

We present the fabrication of vertically aligned cobalt nanowire arrays on planar surfaces as well as preliminary field-emission (FE) experiments using them as cold electron cathodes. These arrays are obtained by electrodeposition into nanoporous templates on Au/Ti/Si substrates at very low temperature (

We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have a uniform diameter of similar to40 nm and a very large aspect ratio (similar to500). The diameter of the nanowires is small enough to ensure a one-dimensional superconducting regime in a wide temperature range below T-c. The non-zero resistance in the superconducting state and its variation caused by fluctuations of the superconducting order parameter were measured versus temperature, magnetic field, and applied dc current (or voltage). The current-induced breakdowns in the voltage-current characteristics may be explained by the formation of phase slip centres. Moreover, dc voltage driven measurements reveal the existence of a new S-shape behaviour near the formation of these phase slip centres.

The cathodic deposition of iron–cobalt alloys inside the pores of anodically formed nanoporous silicon (PS) from p-type Si substrate is investigated with respect to the electrolyte composition. The samples were characterized by scanning electron microscopy, energy dispersive spectrometry, Auger electron spectroscopy, and Fourier transform infrared spectroscopy. Results showed that the nucleation of pure cobalt started at the bottom of the pores and the nucleation of pure iron occurred all over the pore walls, leading to a preferential deposition on top surface of the porous layer. Nevertheless, a low concentration of Co2+ ions (5 at.%) in the electrolyte drastically improved the penetration of iron into the pores. As a result, a good filling of the pores with Co metal as well as with Fe–Co alloys was achieved. It was also shown that the deposition process oxidizes the structure mainly at the pore walls. The results of our investigation indicate that the mechanisms occurring during the electrodeposition of metals on porous p-type silicon substrates are completely different depending on the kind of electrolyte used: pure iron-based electrolyte or cobalt-based solutions. A complete understanding of the deposition process requires further analyses of the carrier transport in PS and of the charge exchange at the Si/electrolyte and PS/electrolyte interfaces. These new results involving the deposition of iron-group materials into porous p-type silicon are useful for future silicon technologies.

Arrays of Cu/Cu2O nanowires were grown by electrodeposition in the nanopores of track-etched polymer membranes. If an appropriate solution is used, the electrode potential spontaneously oscillates during the application of a constant cathodic current. Both the period of the oscillations and the composition of the nanowires can be controlled by varying the applied current density. A nanocomposite of copper and cuprous oxide is deposited at an applied current over which oscillations occur. In contrast, pure Cu or Cu2O nanowires are obtained at a deposition current out of the range of oscillation. Electrical transport measurements were also performed on these nanowires.

We report a comparative study of the giant magnetoresistance (GMR) in CPP (current perpendicular to the planes) geometry in two different types of multilayered nanowire systems: Co/Cu and Ni80Fe20/Cu. The nanowires were produced in the cylindrical pores of a polymer membrane using a pulsed electrodeposition technique. A GMR ratio as large as 78% was obtained for Ni80Fe20/Cu multilayered nanowires. Using the results of the Valet-Fert model for perpendicular transport we deduce the bulk and interface spin asymmetry coefficients and comparison is made between the two systems.

Arrays of cobalt nanowires of diameter 23-70 nm were grown by electrodeposition. Their magnetic properties are probed using ferromagnetic resonance. Depending on the solution pH and deposition rate, the orientation of the dense planes of the hexagonal structure can be controlled so that its c-axis is oriented either parallel or perpendicular to the wires axis. In particular, the effects of the pH and deposition current on the structural and magnetic properties are considered and it is shown that the wire diameter plays an important role in the final preferred structure by inducing local changes of the pH within the pores.

By electrodeposition of tin inside the pores of a polycarbonate template, nanowires were grown, out of which a single one was contacted electrically so as to form a quasi-one-dimensional superconductor (diameter: 50 nm). A resistive phase-slip center appears as a response to a pulse of supercritical current. Measuring its resistance, and its time of nucleation, gives access to the electron inelastic lifetime, and to the gap relaxation time, respectively, both in the nanosecond range. Finally, the threshold current for passage into the fully normal state indicates a good thermal contact with the polycarbonate matrix. (C) 2004 American Institute of Physics.

The effect of fluorination on the transport properties of three classes of materials is presented. The intercalation of fluorine in graphitized carbon fibres drastically modifies their electrical behaviour. A wide range of conductivities is observed from sigma(300K) similar to 1.5 X 10(5) S cm(-1) for Csimilar to 14F to sigma(300K) similar to 10(2) S cm(-1) for C

Thin films of carbon-boron-nitrogen alloys were prepared by chemical vapor deposition from gaseous mixtures of C2H2, BCl3, NH3, and H-2. Their turbostratic graphitic structure was investigated by electron probe micro analysis (EPMA), X-ray diffraction (XRD), Raman spectroscopy, and nuclear magnetic resonance. Those compounds were shown to be solid solutions with compositions varying in a continuous domain bounded by carbon, boron nitride, and BC3. Measurements of the electrical transport properties (conductivity and Hall coefficient) were performed from 295 down to 4.2 K and in the presence of magnetic fields up to 5 T. The behavior of these solid solutions can be interpreted in terms of a metal-non metal transition, when the carbon content decreases. Heat-treatment of these compounds between 1400 and 2000 degrees C involves strongly modified transport properties. The resistivity of all materials is lowered. But the main property change is that of the magnetoresistance.

Arrays of granular superconducting Pb and Sn nanowires (40 - 55 nm in diameter and 22 or 50 mum long) have been prepared by electrodeposition in nanoporous membranes. A simple technique has been developed to perform electrical transport measurement on a single nanowire. By sweeping the dc current inside the nanowire, we observed the formation of phase-slip-centers far below the critical temperature. In contrast, in voltage-driven experiments, an interesting S-shaped behavior has been observed in the nucleation region of these phase-slip-centers. (C) 2003 American Institute of Physics.

International audience; Crystalline anisotropic magnetoresistance with twofold and eight-fold symmetry in (In,Fe)As ferromagnetic semiconductor Appl. Phys. Lett. 100, 262409 (2012) Charge order suppression, emergence of ferromagnetism and absence of exchange bias effect in Bi0.25Ca0.75MnO3 nanoparticles: Electron paramagnetic resonance and magnetization studies J. Appl. Phys. 111, 123913 (2012) Vacancy mediated room temperature ferromagnetism in Co-doped Dy2O3 Appl. Phys. Lett. 100, 252411 (2012) Synthesis and characterization of Co2FeAl nanowires J. Appl. Phys. 111, 123906 (2012) Synthesis, structure, and magnetic behavior of nanoparticles of cubic ZnMnO3 Appl. Phys. Lett. 100, 252407 (2012) Additional information on Appl. Phys. Lett. Journal Homepage: http://apl.aip.org/ Journal Information: http://apl.aip.org/about/about_the_journal Top downloads: http://apl.aip.org/features/most_downloaded Information for Authors: http://apl.aip.org/authors

A comparison is made between the anomalies in the resistivity of CoCl2-GIC's below the Neel temperature and that of metallic antiferromagnets and magnetic multilayers. Special emphasis is given on the ingredients required for the observation of the anomalous electrical transport properties in these magnetic systems.

The intercalation of fluorine in various types of carbon fibers (PAN-based or pitch-based, asreceived or high-temperature treated) has been investigated at room temperature in the presence of gaseous HF. Stage-1 compounds with C2.5F to C4F compositions are obtained for 10 bar F2 pressures, whereas lower pressures (1 bar F2) lead to stage-2 compounds. Although in higher stages (≥2) the electrical conductivity is generally larger than in the pristine fiber, in stage-1 compounds a drastic increase of resistivity is observed, ρ being more than one order of magnitude larger than that of the starting material. Finally, fluorine-intercalated GICs have been found appropriate to investigate the effects of disorder and reduced dimensionality.

The effect of the electrolyte acidity, or pH, on the structural and magnetic properties of electrodeposited cobalt nanowires has been studied. The main result is that as the pH is lowered from 3.8 down to 2.0, a microstructural change is induced. Ferromagnetic resonance measurements show that at high pH, Co presents an hcp phase with the c-axis aligned perpendicular to the wires, whereas at low pH, a more disordered hcp structure is observed. From the resonance line shape analysis, it is shown that for low-pH Co, no grains oriented with the c-axis perpendicular to the wire are present. The resulting magnetic properties show that for high-pH samples, the effective anisotropy field is weaker than that of the low-pH samples due to the competition between shape anisotropy and the cobalt c-axis magnetocrystalline anisotropy.

We report on the electrical characterization of various types of nanocontacts fabricated by nanoindentation and electrodeposition. Arrays of holes with depths ranging from 0 to 20 nm were produced by nanoindenting at different strengths an Al2O3-50 Angstrom/NiFe-150 Angstrom//Si bilayer. NiFe was then electrodeposited, which led to the growth of particles in the holes. The resistance of the particles was measured with a conducting tip atomic force microscope. Depending on the strength used during the nanoindentation, the resistance ranges from less than 5x10(3) Omega to more than 10(12) Omega. The low-resistance constrictions can be used to study ballistic transport in materials. High-resistance contacts presumably correspond to tunnel nanojunctions. (C) 2002 American Institute of Physics.

We present magnetotransport measurements on single cobalt nanowires fabricated by electrodeposition into nanoporous membranes and contacted by an electron beam lithography technique. Isolated nanowires (up to 20 μm long) are extracted from the nanoporous template and spread over a silicon substrate. Electron-beam lithography allows us to make nanosized multiprobe connections on isolated wires and perform measurements on parts of the nanowire as small as 500 nm. Measurements of different segments of a single 60 nm Co nanowire show the inhomogeneity of magnetization reversal processes along the same wire.

We present a fully elaborated process to grow arrays of metallic nanowires with controlled geometry and density, based on electrochemical filling of nanopores in track-etched templates. Nanowire growth is performed at room temperature, atmospheric pressure and is compatible with low cost fabrication and large surfaces. This technique offers an excellent control of the orientation, shape and nanowires density. It is applied to fabricate field emission arrays with a good control of the emission site density. We have prepared Co, Ni, Cu and Rh nanowires with a height of 3 mu m, a diameter of 80 nm and a density of similar to 10(7) cm(-2). The electron field emission measurements and total energy distributions show that the as-grown nanowires exhibit a complex behaviour, first with emission activation under high field, followed by unstable emission. A model taking into account the effect of an oxide layer covering the nanowire surface is developed to explain this particular field emission behaviour. Finally, we present an in situ cleaning procedure by ion bombardment that collectively removes this oxide layer, leading to a stable and reproducible emission behaviour. After treatment, the emission current density is similar to 1 mA cm(-2) for a 30 V mu m-1 applied electric field.

Cr(2)GeC thin films were grown by magnetron sputtering from elemental targets. Phase-pure Cr(2)GeC was grown directly onto Al(2)O(3)(0001) at temperatures of 700-800 degrees C. These films have an epitaxial component with the well-known epitaxial relationship Cr(2)GeC(0001)//Al(2)O(3)(0001) and Cr(2)GeC(11andlt;(2) overbarandgt;0)//Al(2)O(3)(1andlt;(1)over barandgt;00) or Cr(2)GeC(11andlt;(2) over barandgt;0)//Al(2)O(3)(andlt;(1) over barandgt;2andlt;(1) over barandgt;0). There is also a large secondary grain population with (10andlt;(1)overbarandgt;3) orientation. Deposition onto Al(2)O(3)(0001) with a TiN(111) seed layer and onto MgO(111) yielded growth of globally epitaxial Cr(2)GeC(0001) with a virtually negligible (10andlt;(1) over barandgt;3) contribution. In contrast to the films deposited at 700-800 degrees C, the ones grown at 500-600 degrees C are polycrystalline Cr(2)GeC with (10andlt;(1) over barandgt;0)-dominated orientation; they also exhibit surface segregations of Ge as a consequence of fast Ge diffusion rates along the basal planes. The room-temperature resistivity of our samples is 53-66 mu Omega cm. Temperature-dependent resistivity measurements from 15-295 K show that electron-phonon coupling is important and likely anisotropic, which emphasizes that the electrical transport properties cannot be understood in terms of ground state electronic structure calculations only. Original Publication:Per Eklund, Matthieu Bugnet, Vincent Mauchamp, Sylvain Dubois, Christophe Tromas, Jens Jensen, Luc Piraux, Loiek Gence, Michel Jaouen and Thierry Cabioch, Epitaxial growth and electrical transport properties of Cr(2)GeC thin films, 2011, Physical Review B. Condensed Matter and Materials Physics, (84), 7, 075424.http://dx.doi.org/10.1103/PhysRevB.84.075424Copyright: American Physical Societyhttp://www.aps.org/

We used oxygen ion irradiation to transfer the nanoscale pattern of a porous alumina mask into high-T(C) superconducting thin films. This causes a nanoscale spatial modulation of superconductivity and strongly affects the magneto-transport below T(C), which shows a series of periodic oscillations reminiscent of the Little-Parks effect in superconducting wire networks. This irradiation technique could be extended to other oxide materials in order to induce ordered nanoscale phase segregation.

Disorder-induced phenomena are evidenced in both electrical and thermal transport properties of various graphite host materials with transition metal fluoride (C/sub x/MF/sub y/ with M=Cr, Rh, Au and Ir). The electrical resistivity results are analyzed in the framework of weak-localization and carrier-carrier interaction models for two-dimensional disordered electron systems. Compared to other acceptor compounds, these fluoride GICs exhibit essentially two new features. First, for some highly resistive compounds, the logarithmic increase in resistivity with decreasing temperature starts already at room temperature and is dominant down to the lowest temperature investigated (1.5 K). Second, the effect of disorder is also observable in the temperature dependence of the thermal conductivity and thermoelectric power.

We report and discuss experimental data on the thermoelectric power of magnetic multilayers. Measurements of the thermoelectric power of Fe/Cr, Co/Cu and Fe/Cu multilayers have been carried out in the temperature range 4 K < T < 150 K magnetic fields perpendicular to the layers. All specimens were found to exhibit pronounced magnetothermoelectric power (MTEP) effects correlating with their giant negative magnetoresistance. The main difference between the MTEP and the magnetoresistance is in their temperature dependence. Whereas the magnetoresistance is a decreasing function of temperature, the MTEP, at least in Co/Cu and Fe/Cu multilayers, is very small at low temperature and increases rapidly above 30-40 K. We ascribe this high temperature part of the MTEP to spin-dependent electron-magnon scattering and we propose a theoretical model.

The intercalation process of some d-transition metal fluorides in graphite has been investigated using anhydrous liquid HF. C(x)MF(y) GICs have been obtained for M = Cr, Rh, Ir and Au. The charge transfer has been evaluated from optical reflectivity measurements. Comparison has been carried out between electrical conductivity obtained from optical data and from a contactless method. Results on the in-plane electrical resistivity and thermal conductivity are reported. All compounds exhibit a logarithmic resistivity divergence in the low-temperature range due to weak localization and carrier-carrier interaction effects for 2D metals.

The interest in the template-based synthesis of nanomaterials and nanostructures is continuously increasing due to the advantageous features offered by the templates and the ease of processing a large number of nanostructures in parallel. In recent years, nanoporous anodic aluminum oxide (AAO) has been intensively studied and used for that purpose. [1] At present, it is considered one of the most promising templates [2] mainly because of its unique features, which include easily tunable geometrical parameters, mild preparation conditions, and resistance to high temperatures. AAO, whichisatypicalself-orderednanopore-arraymaterialformed by the electrochemical oxidation of Al in acidic solutions, is an excellent starting host material for the fabrication of various nanomaterials and nanostructures. It possesses a hexagonally packed arrangement of nanoscale-sized straight blind holes aligned perpendicular to the surface. The voids of the nanoscale-channeled structure are typically filled with various materials and heterostructures using electrochemical or chemical vapor deposition methods after the elimination of the oxide barrier layer that closes the bottom ends of the holes. While this barrier layer is typically considered undesirable and eliminated, herein we emphasize that the surface of this layer possesses an ordered array of hemispheres that can also be used as a very interesting template. We describe the advantages of the ordered bumpy surface for creating artificial superconducting pinning centers in Nb films deposited on it.