Search

The critical current of a superconducting nanostructure can be suppressed by applying an electric field in its vicinity. This phenomenon is investigated throughout the fabrication and electrical characterization of superconducting tungsten-carbon (W-C) nanostructures grown by Ga+ focused ion beam induced deposition (FIBID). In a 45 nm-wide, 2.7 μm-long W-C nanowire, an increasing side-gate voltage is found to progressively reduce the critical current of the device, down to a full suppression of the superconducting state below its critical temperature. This modulation is accounted for by the squeezing of the superconducting current by the electric field within a theoretical model based on the Ginzburg–Landau theory, in agreement with experimental data. Compared to electron beam lithography or sputtering, the single-step FIBID approach provides with enhanced patterning flexibility and yields nanodevices with figures of merit comparable to those retrieved in other superconducting materials, including Ti, Nb, and Al. Exhibiting a higher critical temperature than most of other superconductors, in which this phenomenon has been observed, as well as a reduced critical value of the gate voltage required to fully suppress superconductivity, W-C deposits are strong candidates for the fabrication of nanodevices based on the electric field-induced superconductivity modulation., P.O. acknowledges Aragón Government for funding. The project that gave rise to these results received the support of a fellowship from “la Caixa” Foundation (ID 100010434). The fellowship code is LCF/BQ/PR19/11700008. Funding from the the European Union’s Horizon 2020 research and innovation programme under the grant agreement No 892427 has been received. Authors acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through Projects MAT2018-102627-T and MAT2017-82970-C2-2-R, from CSIC through project PIE202060E187, and from the Aragón Regional Government (Construyendo Europa desde Aragón) through Project E13_20R, with European Social Fund funding. The microscopy works have been conducted in the Laboratory for Advanced Microscopies (LMA), at the Institute of Nanoscience and Materials of Aragón (INMA)—University of Zaragoza. Authors acknowledge the LMA for offering access to their instruments and expertise. Authors acknowledge the use of the Physical Measurements Service in Servicio General de Apoyo a la Investigación (SAI)—University of Zaragoza. This work has been supported by projects H2020 (FATMOLSproject) and Excellence Unit María de Maeztu (CEX2019-000919-M). This work has been supported by the German Research Foundation (DFG) project #FO 956/6-1 (Germany) and European Cooperation in Science and Technology—COST Action #CA16218 (NANOCOHYBRI). V.M.F. acknowledges partial support from the MEPhI (Russia).

An ultra-fast method to directly grow metallic micro- and nano-structures is introduced. It relies on a Focused Ion Beam (FIB) and a condensed layer of suitable precursor material formed on the substrate under cryogenic conditions. The technique implies cooling the substrate below the condensation temperature of the gaseous precursor material, subsequently irradiating with ions according to the wanted pattern, and posteriorly heating the substrate above the condensation temperature. Here, using W(CO)6 as the precursor material, a Ga+ FIB, and a substrate temperature of -100 °C, W-C metallic layers and nanowires with resolution down to 38 nm have been grown by Cryogenic Focused Ion Beam Induced Deposition (Cryo-FIBID). The most important advantages of Cryo-FIBID are the fast growth rate (about 600 times higher than conventional FIBID with the precursor material in gas phase) and the low ion irradiation dose required (∼50 μC/cm2), which gives rise to very low Ga concentrations in the grown material and in the substrate (≤0.2%). Electrical measurements indicate that W-C layers and nanowires grown by Cryo-FIBID exhibit metallic resistivity. These features pave the way for the use of Cryo-FIBID in various applications in micro- and nano-lithography such as circuit editing, photomask repair, hard masks, and the growth of nanowires and contacts. As a proof of concept, we show the use of Cryo-FIBID to grow metallic contacts on a Pt-C nanowire and investigate its transport properties. The contacts have been grown in less than one minute, which is considerably faster than the time needed to grow the same contacts with conventional FIBID, around 10 hours., Authors acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) through the projects MAT2017-82970-C1 and MAT2017-82970-C2, from CSIC through the project PIE201760E027 and from the Aragon Regional Government (Construyendo Europa desde Aragón) through projects E13_17R and LMP33_18, with European Social Fund funding. R. C. acknowledges Juan de la Cierva Incorporación 2014 program. S. S. acknowledges the support of an Erasmus+ scholarship to fund his stay at University of Zaragoza from J. W. Goethe-Universität, Frankfurt am Main, Germany.

Novel physical properties appear when the size of a superconductor is reduced to the nanoscale, in the range of its superconducting coherence length (ξ0). Such nanosuperconductors are being investigated for potential applications in nanoelectronics and quantum computing. The design of three-dimensional nanosuperconductors allows one to conceive novel schemes for such applications. Here, we report for the first time the use of a He+ focused-ion-beam-microscope in combination with the W(CO)6 precursor to grow three-dimensional superconducting hollow nanowires as small as 32 nm in diameter and with an aspect ratio (length/diameter) of as much as 200. Such extreme resolution is achieved by using a small He+ beam spot of 1 nm for the growth of the nanowires. As shown by transmission electron microscopy, they display grains of large size fitting with face-centered cubic WC1–x phase. The nanowires, which are grown vertically to the substrate, are felled on the substrate by means of a nanomanipulator for their electrical characterization. They become superconducting at 6.4 K and show large critical magnetic field and critical current density resulting from their quasi-one-dimensional superconducting character. These results pave the way for future nanoelectronic devices based on three-dimensional nanosuperconductors., This work was supported by the financial support from Spanish Ministry of Economy and Competitiveness through the projects MAT2014-51982-C2-1-R, MAT2014-51982-C2-2-R, MAT2017-82970-C2-2-R, and from regional Gobierno de Aragon through project E26 and E81 with European Social Fund. R.C. acknowledges Juan de la Cierva-Incorporacion 2014 program. This project has received funding from the EU-H2020 research and innovation programme under Grant Agreement No. 654360 NFFA-Europe.

Focused ion beam induced deposition (FIBID) is a nanopatterning technique that uses a focused beam of charged ions to decompose a gaseous precursor. So far, the flexible patterning capabilities of FIBID have been widely exploited in the fabrication of superconducting nanostructures, using the W(CO)6 precursor mostly in combination with a focused beam of Ga+ ions. Here, the fabrication and characterization of superconducting in-plane tungsten-carbon (W-C) nanostructures by He+ FIBID of the W(CO)6 precursor is reported. A patterning resolution of 10 nm has been achieved, which is virtually unattainable for Ga+ FIBID. When the nanowires are patterned with widths of 20 nm and above, the deposited material is superconducting below 3.5–4 K. In addition, nanowires with widths of 60 and 90 nm have been found to sustain long-range controlled nonlocal superconducting vortex transfer along 3 μm. Overall, these findings strengthen the capabilities of He+ FIBID of W-C in the growth and patterning of in-plane superconducting nanodevices., P Orús acknowledges Aragón Government for funding. This work was supported by a STSM grant from COST Action CA16218. The HIM works were performed in the Ion Beam Center at the Helmholz-Zentrum Dresden-Rossendorf, the access to which and whose support is acknowledged. The project that gave rise to these results received the support of a fellowship from 'la Caixa' Foundation (ID 100010434). The fellowship code is LCF/BQ/PR19/11700008. Authors acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through Projects MAT2018-102627-T and MAT2017-82970-C2, from CSIC through project PIE202060E187, and from the Aragon Regional Government (Construyendo Europa desde Aragón) through Project E13_20R, with European Social Fund funding.

Currently, the patterning of innovative three-dimensional (3D) nano-objects is required for the development of future advanced electronic components. Helium ion microscopy in combination with a precursor gas can be used for direct writing of three-dimensional nanostructures with a precise control of their geometry, and a significantly higher aspect ratio than other additive manufacturing technologies. We report here on the deposition of 3D hollow tungsten carbide nanowires with tailored diameters by tuning two key growth parameters, namely current and dose of the ion beam. Our results show the control of geometry in 3D hollow nanowires, with outer and inner diameters ranging from 36 to 142 nm and from 5 to 28 nm, respectively; and lengths from 0.5 to 8.9 µm. Transmission electron microscopy experiments indicate that the nanowires have a microstructure of large grains with a crystalline structure compatible with the face-centered cubic WC1−x phase. In addition, 3D electron tomographic reconstructions show that the hollow center of the nanowires is present along the whole nanowire length. Moreover, these nanowires become superconducting at 6.8 K and show high values of critical magnetic field and critical current density. Consequently, these 3D nano-objects could be implemented as components in the next generation of electronics, such as nano-antennas and sensors, based on 3D superconducting architectures.

Under high-enough values of perpendicularly-applied magnetic feld and current, a type-II superconductor presents a fnite resistance caused by the vortex motion driven by the Lorentz force. To recover the dissipation-free conduction state, strategies for minimizing vortex motion have been intensely studied in the last decades. However, the non-local vortex motion, arising in areas depleted of current, has been scarcely investigated despite its potential application for logic devices. Here, we propose a route to transfer vortices carried by non-local motion through long distances (up to 10 micrometers) in 50nm-wide superconducting WC nanowires grown by Ga+ Focused Ion Beam Induced Deposition. A giant non-local electrical resistance of 36Ω has been measured at 2K in 3μm-long nanowires, which is 40 times higher than signals reported for wider wires of other superconductors. This giant efect is accounted for by the existence of a strong edge confnement potential that hampers transversal vortex displacements, allowing the long-range coherent displacement of a single vortex row along the superconducting channel. Experimental results are in good agreement with numerical simulations of vortex dynamics based on the time-dependent Ginzburg-Landau equations. Our results pave the way for future developments on information technologies built upon single vortex manipulation in nano-superconductors., Tis work was supported by the fnancial support from Spanish Ministry of Economy and Competitiveness through the projects MAT2015-69725-REDT, MAT2017-82970-C2-1-R and MAT2017-82970-C2-2-R, PIE201760E027, including FEDER funding, FIS2017-84330-R, MDM-2014-0377, FIS2016-80434-P and the Fundación Ramón Areces, EU ERC (Grant Agreement No. 679080), COST Grant No. CA16128 and STSM Grant from COST Action CA16218, and from regional Gobierno de Aragón (grants E13_17R and E28_17R) with European Social Fund (Construyendo Europa desde Aragón) and Comunidad de Madrid through project Nanofrontmag-CM (Grant No. S2013/MIT-2850). R.C. acknowledges Juan de la Cierva-Incorporación 2014 program.

The future technological impact of smaller, faster and more efficient spintronic devices compared to current technologies inspires the quest of new approaches and strategies. Emerging non-conventional nanofabrication tools are required for this purpose. One attractive technique is focused electron beam induced deposition, a direct-writing process of ferromagnetic nano-objects. Here, we report the fabrication of highly pure iron wires with one-dimensional thickness modulation using diiron nonacarbonyl, Fe2(CO)9 as a starting material. For that purpose, we employ a strategy for the electron beam scanning method, in which the beam spots are separated a certain distance from each other in one direction during the deposition process. Magnetic properties of the wires have been experimentally studied by magneto-optical-Kerr microscopy and supported by micromagnetic simulations. Our results suggest that the thickness modulation induces a local magnetic anisotropy along the short axis on the iron wire, which is not present in wires with a uniform thickness. By the proposed writing strategy, the switching field in such modulated wires could be controlled due to changes in magnetostatic interactions. Based on our outcomes, we conjecture that this procedure can be valuable in research on the impact of one-dimensional thickness modulation in nano-objects and future spintronic devices. Display Omitted New way to fabricate nanowires with 1D thickness modulation by FEBID.Switching field of magnetic wires vs. 1D thickness modulation is controlled.The observed magnetic properties rely on changes in magnetostatic interactions.

One of the main features of any lithography technique is its resolution, generally maximized for a single isolated object. However, in most cases, functional devices call for highly dense arrays of nanostructures, the fabrication of which is generally challenging. Here, we show the growth of arrays of densely packed isolated nanowires based on the use of focused beam induced deposition plus Ar+ milling. The growth strategy presented herein allows the creation of films showing thickness modulation with periodicity determined by the beam scan pitch. The subsequent Ar+ milling translates such modulation into an array of isolated nanowires. This approach has been applied to grow arrays of W-based nanowires by focused ion beam induced deposition and Co nanowires by focused electron beam induced deposition, achieving linear densities up to 2.5 × 107 nanowires/cm (one nanowire every 40 nm). These results open the route for specific applications in nanomagnetism, nanosuperconductivity, and nanophotonics, where arrays of densely packed isolated nanowires grown by focused beam deposition are required. © 2014 American Chemical Society., This work was supported by Spanish Ministry of Economy and Competitivity through Project No. MAT2011-27553-C02, including FEDER funds and by the Aragon Regional Government.

The implementation of three-dimensional (3D) nano-objects as building blocks for the next generation of electro-mechanical, memory and sensing nano-devices is at the forefront of technology. The direct writing of functional 3D nanostructures is made feasible by using a method based on focused ion beam induced deposition (FIBID). We use this technique to grow horizontally suspended tungsten nanowires and then study their nano-mechanical properties by three-point bending method with atomic force microscopy. These measurements reveal that these nanowires exhibit a yield strength up to 12 times higher than that of the bulk tungsten, and near the theoretical value of 0.1 times the Young's modulus (E). We find a size dependence of E that is adequately described by a core-shell model, which has been confirmed by transmission electron microscopy and compositional analysis at the nanoscale. Additionally, we show that experimental resonance frequencies of suspended nanowires (in the MHz range) are in good agreement with theoretical values. These extraordinary mechanical properties are key to designing electro-mechanically robust nanodevices based on FIBID tungsten nanowires., This work was supported by the financial support from Spanish Ministry of Economy and Competitiveness through the projects CSD2010-00024, MAT2014-51982-C2-1-R, MAT2014-51982-C2-2-R, TEC2015-69864-R, MAT2015-69725-REDT (including FEDER funding) and from regional Gobierno de Aragón through project E26 with European Social Fund and COST-Celina project. R C acknowledges Juan de la Cierva-Incorporación 2014 program. J P-N grant is funded by the Ayuda para Contratos Predoctorales para la Formación de Doctores, Convocatoria Res. 05/06/15 (BOE 12/06/15) of the Secretaría de Estado de Investigación, Desarrollo e Innovación in the Subprograma Estatal de Formación of the Spanish Ministry of Economy and Competitiveness (MINECO) with the participation of the European Social Fund.

Iron nanostructures grown by focused electron beam induced deposition (FEBID) are promising for applications in magnetic sensing, storage and logic. Such applications require a precise design and determination of the coercive field (H C), which depends on the shape of the nanostructure. In the present work, we have used the Fe2(CO)9 precursor to grow iron nanowires by FEBID in the thickness range from 10 to 45 nm and width range from 50 to 500 nm. These nanowires exhibit an Fe content between 80 and 85%, thus giving a high ferromagnetic signal. Magneto-optical Kerr characterization indicates that H C decreases for increasing thickness and width, providing a route to control the magnetization reversal field through the modification of the nanowire dimensions. Transmission electron microscopy experiments indicate that these wires have a bell-type shape with a surface oxide layer of about 5 nm. Such features are decisive in the actual value of H C as micromagnetic simulations demonstrate. These results will help to make appropriate designs of magnetic nanowires grown by FEBID., This work was supported by Spanish Ministry of Economy and Competitivity through project No. MAT2011-27553-C02, MAT2011-28532-C03-02 and MAT2014-51982-C2-1-R, including FEDER funds and by the Aragon Regional Government.

This chapter is devoted to the fabrication and advanced characterization of cobalt nanowires grown by focused electron beam induced deposition. After showing how to pattern pure Cobalt wires by choosing appropriate growth conditions, we investigate the conduction of domain walls in this type of nanowires for storage and logic applications. Moreover, we pattern out-of-plane nanostructures, opening a new route to investigate three-dimensional spintronic systems.

In this chapter we present the fabrication and characterization of superconducting tungsten nanodeposits grown by focused ion beam induced deposition. First, we study the influence of some deposition parameters, such as ion beam voltage, ion beam current, and incidence angle of the focused ion beam, on the nanodeposits’ composition. Second, we present the superconducting properties of tungsten deposits of varying width, from microwires to ultranarrow nanowires of 50 nm width, by means of magnetotransport measurements. Finally, we study the nonlocal voltage generated in tungsten nanowires by nonlocal magnetotransport measurements. The results allow us to link this kind of superconducting nanostructures to potential applications in nanotechnology.

Applications based on the movement of domain walls (DWs) in magnetic nanowires (NWs) require a good DW conduit behavior, i.e. a significant difference between DW nucleation and propagation fields. In this work, we have systematically studied how this property evolves in cobalt NWs grown by focused electron beam induced deposition (FEBID) as a function of global gallium irradiation, for irradiation doses up to 1.24 × 1017 ions cm-2. Whereas for high doses the DW conduit is lost, below 6.42 × 1015 ions cm-2 the difference between the two fields increases with irradiation, becoming up to ∼9 times larger than for non-irradiated wires, due to a strong increase in the nucleation field, while the propagation field remains approximately constant. This behavior stems from two effects. The first effect is a decrease in the magnetic volume of the parasitic halo around the NW, typically present in FEBID nanostructures, leading to the disappearance of weak nucleation centers. The second effect is the formation of a 20 nm outer shell with Co crystals about twice the size of those forming the NW core, causing a net increase of the local magnetocrystalline anisotropy. The results presented here are important for the potential use of magnetic NWs grown by FEBID in DW-based devices, and might also be of interest for magnetic NWs fabricated by other techniques. © 2013 IOP Publishing Ltd., This research was supported by the MAT2011-27553-C02 and MAT2011-28532-CO3-02 projects funded by the Spanish Ministry of Economy (including FEDER funding), by the I-LINK0026 project funded by the Spanish CSIC, by a Marie Curie Intra European Fellowship project No. 251698: 3DMAGNANOW and by an Advanced Grant project No. 247368: 3SPIN, both funded by the 7th European Community Framework Programme.

Under the terms of the Creative Commons Attribution 3.0 Unported License.-- et al., Direct observation of domain wall (DW) nucleation and propagation in focused electron beam induced deposited Co nanowires as a function of their dimensions was carried out by Lorentz microscopy (LTEM) upon in situ application of magnetic field. Optimal dimensions favoring the unambiguous DW nucleation/propagation required for applications were found in 500-nm-wide and 13-nm-thick Co nanowires, with a maximum nucleation field and the largest gap between nucleation and propagation fields. The internal DW structures were resolved using the transport-of-intensity equation formalism in LTEM images and showed that the optimal nanowire dimensions correspond to the crossover between the nucleation of transverse and vortex walls., This work was supported by Spanish Ministry of Economy and Competitivity through project Nos. MAT2011-28532-C03-01, MAT2011-28532-C03-02, and MAT2011-27553-C02, including FEDER funds, by Junta de Castilla y Leon through the Project SA163A12, and by the European Union Seventh Framework Programme under Grant Agreement 312483—ESTEEM2 (Integrated Infrastructure Initiative—I3) and TRAIN2 project.

A detailed description of the use of the focused ion beam (FIB) to grow electrical contacts is presented. The combination of FIB with precursor compounds, which are delivered on the area of interest by means of gas-injection systems, allows the growth of electrical contacts with nanometric resolution on targeted places. The technique has been coined focused ion beam-induced deposition (FIBID). Pros and cons with respect to other existing techniques for contacting are discussed. The FIBID contacts reported in this chapter are based on the use of Pt and W precursors, which result in the growth of deposits with resistivities down to 100 μΩ cm without any post-treatment. A comparison of FIBID with focused electron beam-induced deposition, the sister technique that uses focused electrons instead of ions, is also presented. The steps to follow in order to be successful in the contacting process by means of FIBID are described. Examples of the contacting to individual nanowires and nanoparticles carried out in our laboratory are shown, together with the corresponding four-probe transport measurements. Below 5 K, W deposits are superconducting and can be therefore used for zero-resistance lead contacts, superconductor-based nanocontacts and probing of proximity effects, opening new perspectives as described here., Financial support by the Spanish Ministry of Economy (through project MAT2011-27553-C02, including FEDER funding) and the Aragón Regional Government is acknowledged.

We have successfully grown ultrasmall cobalt nanostructures (lateral size below 30 nm) by optimization of the growth conditions using focused electron-beam-induced deposition techniques. This direct-write nanolithography technique is thus shown to produce unprecedented resolution in the growth of magnetic nanostructures. The challenging magnetic characterization of such small structures is here carried out by means of electron holography techniques. Apart from growing ultranarrow nanowires, very small Hall sensors have been created and their large response has been unveiled.

3 páginas, 3 figuras.-- et al., We study the electrical resistivity of individual Bi nanowires of diameter 100 nm fabricated by electrodeposition using a four-probe method in the temperature range 5–300 K with magnetic fields up to 90 kOe. Low-resistance Ohmic contacts to individual Bi nanowires are achieved using a focused ion beam to deposit W-based nanocontacts. Magnetoresistance measurements show evidence for weak antilocalization at temperatures below 10 K, with a phase-breaking length of 100 nm., This work was supported by Spanish Ministry of Science (through Project Nos. MAT2007-65965-C02-02 and MAT2008-06567-C02) including FEDER funding and the Aragon Regional Government. N. Marcano and S. Sangiao acknowledge financial support from Spanish CSIC (JAE-doc program) and Spanish MEC (FPU program).

We present a study of the transport properties of Pt-C nanowires created by focused-ion-beam (FIB)-induced deposition. By means of the measurement of the resistance while the deposit is being performed, we observe a progressive decrease in the nanowire resistivity with thickness, changing from ${10}^{8}\text{ }\ensuremath{\mu}\ensuremath{\Omega}\text{ }\text{cm}$ for thickness $\ensuremath{\sim}20\text{ }\text{nm}$ to a lowest saturated value of $700\text{ }\ensuremath{\mu}\ensuremath{\Omega}\text{ }\text{cm}$ for thickness $g150\text{ }\text{nm}$. Spectroscopy analysis indicates that this dependence on thickness is caused by a gradient in the metal-carbon ratio as the deposit is grown. We have fabricated nanowires in different ranges of resistivity and studied their conduction mechanism as a function of temperature. A metal-insulator transition as a function of the nanowire thickness is observed. The results will be discussed in terms of the Mott-Anderson theory for noncrystalline materials. An exponential decrease in the conductance with the electric field is found for the most resistive samples, a phenomenon understood by the theory of hopping in lightly doped semiconductors under strong electric fields. This work explains the important discrepancies found in the literature for Pt-C nanostructures grown by FIB and opens the possibility to tune the transport properties of this material by an appropriate selection of the growth parameters.

The domain wall nucleation and propagation fields in cobalt nanowires grown by focused electron beam induced deposition are measured using spatially resolved magneto-optical Kerr effect. The study was systematically done for wire widths from 600 to 150 nm, finding significant differences in the value of both fields for the wires, indicating high quality domain wall conduit behavior. The extreme simplicity and flexibility of this technique with respect to the multistep lithographic processes used nowadays opens a different route to create magnetic nanostructures with a good control of the domain wall motion.

6 pages, 6 figures.-- PACS nrs.: 75.47.-m, 73.63.-b, 81.07.-b, 81.15.Jj., High-quality cobalt nanowires have been grown by focused-electron-beam-induced deposition (FEBID) and their magnetic and transport properties determined. The nanowires contain up to about 95% Co atomic percentage, as measured by EDX spectroscopy, which remarkably represents a high value compared with other metal deposits grown by the same technique. The Co content has been found to correlate with the beam current used for the growth. The magnetotransport properties have been studied on individual nanowires through 4-probe measurements. For the nanowires with the highest Co content, the resistivity at room temperature is low (~40 µΩ cm), and shows metallic temperature dependence. The magnetotransport properties clearly demonstrate the ferromagnetic nature of the nanowire, with a saturation magnetization of Ms = 1329 ± 20 emu cm−3, very close to the bulk one. Due to the local character of this type of growth at targeted places and its high lateral resolution, these results pave the way for the creation of magnetic nanostructures and devices with the full potentiality of high-quality Co., Financial support by the Spanish Ministry of Science (through projects MAT2005-05565-C02 and MAT2008-06567-C02 including FEDER funding) and the Aragon Regional Government is acknowledged.

We systematically study individual micro- and nanometric polycrystalline cobalt wires grown by focused-electron-beam-induced-deposition. The deposits were grown in a range of aspect ratios varying from 1 up to 26. The minimum lateral dimension of the nanowires was 150 nm, for a thickness of 40 nm. Atomic force microscopy images show beam-current-dependent profiles, associated with different regimes of deposition. The magnetization reversal of individual nanowires is studied by means of the spatially resolved magneto-optical Kerr effect. Abrupt switching is observed, with a systematic dependence on the wire's dimensions. This dependence of the coercive field is understood in magnetostatic terms, and agrees well with previous results on cobalt wires grown with different techniques. The influence of compositional gradients along the structural profile on the magnetic reversal is studied by using micromagnetic simulations. This work demonstrates the feasibility of using this technique to fabricate highly pure magnetic nanostructures, and highlights the advantages and disadvantages of the technique with respect to more conventional ones.

Here we present a 'circuit edit' concept for superconducting microcircuits that operate at T≤4.2 K making use of superconducting material fabricated using focused ion beam induced deposition (FIBID) with W(CO)6 as the precursor gas. This material has been recently used to fabricate superconducting nanowires with a critical temperature of 5.2 K. Circuit edit consists of using FIB technology with the possibilities for local patterning with nanometer resolution, to modify or repair highly valuable low- TC superconducting devices such SQUIDs, Josephson junction array voltage standards, or transition edge sensors.

We report transport measurements of superconducting amorphous W-based nanodeposits fabricated by focused-ion-beam-induced-deposition (FIBID) technique using W(CO)6 as the gas precursor. We have found that nanowires with width down to ˜100 nm can be grown by FIBID, maintaining the relatively high TC of �5.2 K shown by wider nanodeposits. The critical current found in these nanowires is in the range of 0.8 mA/?m2 at 2 K. At that temperature the critical field HC2 is found to be ?8 T. As previously shown by STM measurements [I. Guillam�n et al., New Journal of Physics 10, 093005 (2008)], these nanodeposits closely follow the BCS theory and are very stable under ambient conditions. All these features pave the way for a wide range of applications of these FIBID W-based nanowires in the field of Nanotechnology.