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Among the different types of switchable molecular compounds, sublimable Fe(II) SCO molecules provide a suitable platform to develop smart devices that respond to external stimuli. Here we report the synthesis, crystallographic structure and magnetic properties of three new neutral Fe(II) SCO molecules belonging to the {Fe[H2B(pz)2]2(L)} family with bidentate-alpha-diimine ligands L = 3-(pyridin-2-yl)-[1,2,3]triazolo[1,5-a]pyridine (tzpy), 5,5,6,6-tetrahydro-4H,4H-2,2-bi(1,3-thiazine) (btz) and 4,4,5,5-tetrahydro-2,2-bithiazole (bt) (1, 2 and 3, respectively), as well as two solvated forms of 1 and 3. All three desolvated compounds present thermal- and light-induced SCO transitions with different degrees of cooperativity and effectiveness. Furthermore, 1 and 2 are demonstrated to be sublimable under HV conditions affording homogeneous thin films 200 nm thick (TF1 and TF2) that retain the chemical integrity of the original molecules regardless the deposition surface. The SCO behaviour of the films is characterized by XAS technique revealing the partial retainment of both thermal- and light-induced spin transitions, yet losing the cooperativity. Finally, SCO/2D horizontal hybrid devices based on CVD-graphene are produced using these films. Being the first ones of this type utilizing molecules of {Fe[H2B(pz)2]2(L)} family, with L = tzpy and btz, the devices have allowed the successful detection of the thermal SCO transition through the electric properties of the CVD-graphene., Comment: 20 pages, 8 figures

INTRODUCCIÓN: La fascitis necrotizante cervical es una entidad poco frecuente en cabeza y el cuello (3) , pero su importancia está dada por la elevada tasa de mortalidad. OBJETIVO: Describir la experiencia en fascitis necrotizante cervical en el Hospital General Dr. Manuel Gea González. DISEÑO: Estudio descriptivo, retrospectivo y transversal. MATERIALES Y MÉTODOS: Estudio descriptivo, retrospectivo y transversal de historias clínicas del servicio de Otorrinolaringología y Cirugía de Cabeza y Cuello del Hospital General Dr. Manuel Gea González, de 2011 a 2017. RESULTADOS: Se incluyeron 11 historias clínicas con diagnóstico de fascitis necrotizante cervical, de las cuales 8 (72,7%) eran hombres y 3 (27,2%) mujeres, con una edad promedio de 49,1 años. Cinco (45,4%) pacientes debutaron con diabetes mellitus tipo 2. El origen de la infección fue odontogénico en tres (27,2%) pacientes. Los microorganismos más frecuentes fueron: Klebsiella pneumoniae, Streptococcus anginosus y Staphylococcus epidermidis. Los 11 pacientes (100%) fueron intervenidos quirúrgicamente e impregnados con antimicrobianos empíricos, que posteriormente fueron modificados o no, según los resultados del antibiograma. La hospitalización promedio fue de 18,7 días. Tres (27,2%) pacientes presentaron mediastinitis como complicación. Hubo dos muertes (18,1%). CONCLUSIÓN: El diagnóstico temprano y el tratamiento antimicrobiano empírico y quirúrgico agresivo pueden reducir significativamente la morbilidad y la mortalidad. IMPORTANCIA CLINICA: No hay muchos reportes de casos de esta patología en América Latina, por lo cual queremos describir la experiencia en nuestro Hospital. Palabras clave: fascitis necrotizante cervical, infecciones de piel y tejidos blandos, fascitis necrotizante craneocervical.

Hybrid devices based on spin-crossover (SCO)/2D heterostructures grant a highly sensitive platform to detect the spin transition in the molecular SCO component and tune the properties of the 2D material. However, the fragility of the SCO materials upon thermal treatment, light irradiation or contact with surfaces and the methodologies used for their processing have limited their applicability. Here, we report an easily processable and robust SCO/2D hybrid device with outstanding performance based on the sublimable SCO [Fe(Pyrz)2] molecule deposited over CVD-graphene, which is fully compatible with electronics industry protocols. Thus, a novel methodology based on growing an elusive polymorph of [Fe(Pyrz)2] (tetragonal phase) over graphene is developed that allows us to electrically detect a fast and effective light-induced spin transition in the devices (~50% yield in 5 minutes). Such performance can be enhanced even more when a flexible polymeric layer of PMMA is inserted in between the two active components in a contactless configuration, reaching a ~100 % yield in 5 minutes., 25 pages, 5 figures

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.

Due to their anisotropy, layered materials are excellent candidates for studying the interplay between the in-plane and out-of-plane entanglement in strongly correlated systems. A relevant example is provided by 1T-TaS2, which exhibits a multifaceted electronic and magnetic scenario due to the existence of several charge density wave (CDW) configurations. It includes quantum hidden phases, superconductivity and exotic quantum spin liquid (QSL) states, which are highly dependent on the out-of-plane stacking of the CDW. In this system, the interlayer stacking of the CDW is crucial for interpreting the underlying electronic and magnetic phase diagram. Here, atomically thin-layers of 1T-TaS2 are integrated in vertical van der Waals heterostructures based on few-layers graphene contacts and their electrical transport properties are measured. Different activation energies in the conductance and a gap at the Fermi level are clearly observed. Our experimental findings are supported by fully self-consistent DFT+U calculations, which evidence the presence of an energy gap in the few-layer limit, not necessarily coming from the formation of out-of-plane spin-paired bilayers at low temperatures, as previously proposed for the bulk. These results highlight dimensionality as a key effect for understanding quantum materials as 1T-TaS2, enabling the possible experimental realization of low-dimensional QSLs.

Van der Waals heterostructures (vdWHs) allow the assembly of high-crystalline two-dimensional (2D) materials in order to explore dimensionality effects in strongly correlated systems and the emergence of potential new physical scenarios. In this work, it is illustrated the feasibility to integrate 2D materials in-between 2D superconductors. Particularly, it is presented the fabrication and electrical characterization of vertical vdWHs based on air-unstable atomically-thin transition metal dichalcogenides formed by NbSe2/TaS2/NbSe2 stacks, with TaS2 being the insulator 1T-TaS2 or the metal 2H-TaS2. Phase transitions as 1T-TaS2 charge density wave and NbSe2 superconductivity are detected. An enhancement of the vdWH resistance due to Andreev reflections is observed below the superconducting transition temperature of the NbSe2 flakes. Moreover, in the NbSe2 superconducting state, the field and temperature dependence of the normalized conductance is analyzed within the Dynes' model and the overall behavior is consistent with the Bardeen-Cooper-Schrieffer theory. This vdWH approach can be extended to other 2D materials, such as 2D magnets or topological insulators, with the aim of exploring the new emergent properties that may arise from such combinations., Comment: 18 pages, 5 figures

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)

Due to their anisotropy, layered materials are excellent candidates for studying the interplay between the in-plane and out-of-plane entanglement in strongly correlated systems. A relevant example is provided by 1T-TaS2, which exhibits a multifaceted electronic and magnetic scenario due to the existence of several charge density wave (CDW) configurations. It includes quantum hidden phases, superconductivity and exotic quantum spin liquid (QSL) states, which are highly dependent on the out-of-plane stacking of the CDW. In this system, the interlayer stacking of the CDW is crucial for the interpretation of the underlying electronic and magnetic phase diagram. Here, thin-layers of 1T-TaS2 are integrated in vertical van der Waals heterostructures based on few-layer graphene (FLG) contacts and their electrical transport properties are measured. Different activation energies in the conductance and a gap at the Fermi level are clearly observed. Our experimental findings are supported by fully self-consistent DFT+U calculations, which evidence the presence of an energy gap in the few-layer limit, not necessarily coming from the formation of out-of-plane spin-paired bilayers at low temperatures, as previously proposed for the bulk. These results highlight dimensionality as a key effect for understanding the properties of 1T-TaS2 and opens the door to the possible experimental realization of low-dimensional QSLs., Main Text (5 figures)

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.

Novel schemes based on the design of complex three-dimensional (3D) nanoscale architectures are required for the development of the next generation of advanced electronic components. He+ focused-ion-beam (FIB) microscopy in combination with a precursor gas allows one to fabricate 3D nanostructures with an extreme resolution and a considerably higher aspect ratio than FIB-based methods, such as Ga+ FIB-induced deposition, or other additive manufacturing technologies. In this work, we report the fabrication of 3D tungsten carbide nanohelices with on-demand geometries via controlling key deposition parameters. Our results show the smallest and highest-densely packed nanohelix ever fabricated so far, with dimensions of 100 nm in diameter and aspect ratio up to 65. These nanohelices become superconducting at 7 K and show a large critical magnetic field and critical current density. In addition, given its helical 3D geometry, fingerprints of vortex and phase-slip patterns are experimentally identified and supported by numerical simulations based on the time-dependent Ginzburg–Landau equation. These results can be understood by the helical geometry that induces specific superconducting properties and paves the way for future electronic components, such as sensors, energy storage elements, and nanoantennas, based on 3D compact nanosuperconductors.

This article belongs to the Special Issue Multi-Dimensional Direct-Write Nanofabrication., In this contribution, we compare the performance of Focused Electron Beam-induced Deposition (FEBID) and Focused Ion Beam-induced Deposition (FIBID) at room temperature and under cryogenic conditions (the prefix “Cryo” is used here for cryogenic). Under cryogenic conditions, the precursor material condensates on the substrate, forming a layer that is several nm thick. Its subsequent exposure to a focused electron or ion beam and posterior heating to 50 °C reveals the deposit. Due to the extremely low charge dose required, Cryo-FEBID and Cryo-FIBID are found to excel in terms of growth rate, which is typically a few hundred/thousand times higher than room-temperature deposition. Cryo-FIBID using the W(CO)6 precursor has demonstrated the growth of metallic deposits, with resistivity not far from the corresponding deposits grown at room temperature. This paves the way for its application in circuit edit and the fast and direct growth of micro/nano-electrical contacts with decreased ion damage. The last part of the contribution is dedicated to the comparison of these techniques with other charge-based lithography techniques in terms of the charge dose required and process complexity. The comparison indicates that Cryo-FIBID is very competitive and shows great potential for future lithography developments., This research was funded by the Spanish Ministry of Science, grant numbers MAT2017-82970-C2-2-R and MAT2018-102627-T, and by the Aragon Government (Construyendo Europa desde Aragón), grant numbers E13_17R and LMP33_18, with the European Social Fund.

The microscopic mechanism behind the all optical switching (AOS) in ferromagnets has triggered intense scientific debate. Here, the microscopic three-temperature model is utilized to describe AOS in a perpendicularly magnetized ferromagnetic Co/Pt system. We demonstrate that AOS in such a ferromagnet can be explained with the Inverse Faraday Effect (IFE). The influence of the strength and lifetime of the IFE induced field pulse on the switching process are investigated. We found that because of strong spin-orbit coupling, the minimal lifetime of the IFE needed to obtain switching is of the order of 0.1 ps, which is shorter than previously assumed. Moreover, spatial images of the domain pattern after AOS in Co/Pt, as well as their dependence on applying an opposite magnetic field, are qualitatively reproduced.

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.

In Section 3 [...]

Functional nanostructures fabricated by focused electron/ion beam induced processing (FEBIP/FIBIP) open a promising route for applications in nanoelectronics. Such developments rely on the exploration of new advanced materials. We report here the successful fabrication of nickel-based deposits by FEBIP/FIBIP using bis(methyl cyclopentadienyl)nickel as a precursor. In particular, binary compounds such as nickel oxide (NiO) are synthesized by using an in situ two-step process at room temperature. By this method, as-grown Ni deposits transform into homogeneous NiO deposits using focused electron beam irradiation under O2 flux. This procedure is effective in producing highly pure NiO deposits with resistivity of 2000 Ωcm and a polycrystalline structure with face-centred cubic lattice and grains of 5 nm. We demonstrate that systems based on NiO deposits displaying resistance switching and an exchange-bias effect could be grown by FEBIP using optimized parameters. Our results provide a breakthrough towards using these techniques for the fabrication of functional nanodevices.

We review the current status of the use of focused electron beam induced deposition (FEBID) for the growth of magnetic nanostructures. This technique relies on the local dissociation of a precursor gas by means of an electron beam. The most promising results have been obtained using the Co(CO) precursor, where the Co content in the grown nanodeposited material can be tailored up to more than 95 at.%. Functional behaviour of these Co nanodeposits has been observed in applications such as arrays of magnetic dots for information storage and catalytic growth, magnetic tips for scanning probe microscopes, nano-Hall sensors for bead detection, nano-actuated magnetomechanical systems and nanowires for domain-wall manipulation. The review also covers interesting results observed in Fe-based and alloyed nanodeposits. Advantages and disadvantages of FEBID for the growth of magnetic nanostructures are discussed in the article as well as possible future directions in this field., Financial support by several projects is acknowledged: MAT2014-51982-C2-1-R, MAT2014-51982-C2-2-R and MAT2015-69725-REDT from MINECO (including FEDER funding), CELINA COST Action CM1301, Aragón Regional Government through project E26, FP7 Marie Curie Fellowship 3DMAGNANOW, EPSRC Early Career Fellowship EP/M008517/1 and Winton Fellowship.

Focused Electron Beam Induced Processing (FEBIP) using XeF2 gas injection is routinely applied in circuit editing, mask repair and nanolithography to etch semiconducting or metallic materials. Here, we report the use of XeF2-assisted FEBIP for a novel application: the formation of a metal fluoride from a metal layer in the area scanned by the electron beam. Our study focuses on the reaction of cobalt into cobalt trifluoride (CoF3). The objective of the present study is to locally obtain the CoF3 compound out of a cobalt nanostructure. The CoF3 phase has been reported in the past to show antiferromagnetic properties at room temperature, thus ferromagnetic/antiferromagnetic (Co/CoF3) bilayer structures with magnetic exchange bias phenomena could be engineered at the micro/nano scale. Electron Energy Loss Spectroscopy studies presented here demonstrate that CoF3 is efficiently obtained out of Co by means of XeF2-assisted FEBIP, opening the route for future Co/CoF 3-based devices. © 2014 Elsevier B.V. All rights reserved., This work was supported by Spanish Ministry of Economy and Competitivity through project No. MAT2011- 27553-C02, including FEDER funds.

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.

Superconductivity and ferromagnetism are two antagonistic phenomena that combined can lead to a rich phenomenology of interactions, resulting in novel physical properties and unique functionalities. Here we propose an original hybrid system formed by a high-temperature superconducting film, patterned with antidots, and with ferromagnetic nano-rods grown inside them. This particular structure exhibits the synergic influence of superconductor (SC) - ferromagnetic (FM) stray fields, in both the superconducting behaviour of the film and the three-dimensional (3D) magnetic structure of nano-rods. We show that FM stray fields directly influence the critical current density of the superconducting film. Additional functionalities appear due to the interaction of SC stray fields, associated to supercurrent loops, with the non-trivial 3D remanent magnetic structure of FM nano-rods. This work unravels the importance of addressing quantitatively the effect of stray magnetic fields from both, the superconductor and the ferromagnet in hybrid magnetic nano-devices based on high temperature superconductors., This work has been supported by Spanish MINECO and FEDER (MAT2014-51778-C2-1R, CSD2007-0041, MAT2014-51982-C2-1-R and MAT2015-69725-REDT, MAT2016-79426-P), Severo Ochoa SEV2015-0496 program, Generalitat de Catalunya (2014-SGR-00753, 2014-SGR-150, 2014-PROD00059), Aragon regional government projects, including FEDER funding, European Seventh Framework Program (FP7/2007-2013) under grant agreement 312284, EU-NMP-LA-2012-280432 EUROTAPES project and Cost Actions MP1201 and CM1301 (CELINA). A. Sanchez acknowledges a grant from ICREA Academia, funded by the Generalitat de Catalunya. We are grateful to I. Rivas and R. Valero from LMA-INA (Zaragoza, Spain) for experimental help in the cobalt growth and Ar+ milling processes, and Dr C. Magén and Dr. P. Algarabel from LMA-INA (Zaragoza, Spain) for facilitating the use of their high performance computing server to perform the micromagnetic simulations. We acknowledge R. Morales from UPV/EHU and Ikerbasque, A. Fernández-Pacheco from U. Cambridge and S. Valencia from Helmholtz-Zentrum, Berlin for fruitful discussions.

To increase the efficiency of current electronics, a specific challenge for the next generation of memory, sensing and logic devices is to find suitable strategies to move from two- to three-dimensional (3D) architectures. However, the creation of real 3D nano-objects is not trivial. Emerging non-conventional nanofabrication tools are required for this purpose. One attractive method is focused-electron-beam induced deposition (FEBID), a direct-write process of 3D nano-objects. Here, we grow 3D iron and cobalt nanopillars by FEBID using diiron nonacarbonyl Fe2(CO)9, and dicobalt octacarbonyl Co2(CO)8, respectively, as starting materials. In addition, we systematically study the composition of these nanopillars at the sub-nanometer scale by atom probe tomography, explicitly mapping the homogeneity of the radial and longitudinal composition distributions. We show a way of fabricating high-purity 3D vertical nanostructures of ~50 nm in diameter and a few micrometers in length. Our results suggest that the purity of such 3D nanoelements (above 90 at% Fe and above 95 at% Co) is directly linked to their growth regime, in which the selected deposition conditions are crucial for the final quality of the nanostructure. Moreover, we demonstrate that FEBID and the proposed characterization technique not only allow for growth and chemical analysis of single-element structures, but also offers a new way to directly study 3D core–shell architectures. This straightforward concept could establish a promising route to the design of 3D elements for future nano-electronic devices.

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.

7 páginas, 6 figuras, 1 tabla., The silver−copper mixed oxide AgCuO2 (also formulated as Ag2Cu2O4) possesses a peculiar electronic structure in which both Ag and Cu are partially oxidized, with the charge being delocalized among the three elements in the oxide. Accordingly, a quasi-metallic behavior should be expected for this oxide, and indeed bulk transport measurements show conductivity values that are orders of magnitude higher than for other members of this novel oxide family. The presence of silver makes thermal sintering an inadequate method to evaluate true conductivity, and thus such measurements were performed on low density pellets, giving an underestimated value for the conductivity. In the present work we present a new synthetic route for AgCuO2 based on mild hydrothermal reactions that has yielded unprecedented large AgCuO2 single-crystals well over 1 μm in size using temperatures as low as 88 °C. We have used a dual beam instrument to apply nanocontacts to those crystals, allowing the in situ measurement of transport properties of AgCuO2 single crystals. The results show a linear relationship between applied current and measured voltage. The conductivity values obtained are 50 to 300 times higher than those obtained for bulk low density AgCuO2 pellets, thus confirming the high conductivity of this oxide and therefore supporting the delocalized charge observed by spectroscopic techniques., The authors thank financing from Nanoaracat and from the Spanish Ministry of Education and Science through Grants MAT2005-07683-C02-01 and MAT2008-06643-C02-01, and for a FPI fellowship for D.M-R. D.M-R. is also grateful to the CSIC and the European Social Fund for funding through the I3P program.

A two-dimensional lattice of vortices melts into an isotropic liquid with increasing temperature. A microscopic view of the melting transition reveals that this actually occurs in three steps, one of which is an unusual liquid-crystal-like vortex phase.

We study the origin of the strong difference in the resistivity of focused-electron- and focused-Ga-ion-beam-induced deposition (FEBID and FIBID, resp.) of Pt performed in a dual beam equipment using(CH3)3Pt(CpCH3)as the precursor gas. We have performed in-situ and ex-situ resistance measurements in both types of nanodeposits, finding that the resistivity of Pt by FEBID is typically four orders of magnitude higher than Pt by FIBID. In the case of Pt by FEBID, the current-versus-voltage dependence is nonlinear and the resistance-versus-temperature behavior is strongly semiconducting, whereas Pt by FIBID shows linear current-versus-voltage dependence and only slight temperature dependence. The microstructure, as investigated by high-resolution transmission electron microscopy, consists in all cases of Pt single crystals with size about 3 nm embedded in an amorphous carbonaceous matrix. Due to the semiconducting character of the carbon matrix, which is the main component of the deposit, we propose that the transport results can be mapped onto those obtained in semiconducting materials with different degrees of doping. The different transport properties of Pt by FEBID and FIBID are attributed to the higher doping level in the case of FIBID, as given by composition measurements obtained with energy-dispersive X-ray microanalysis.

d ) Institute of Physics, Slovak Academy of Sciences, Dubravska cesta 9, SK-845 36 Bratislava e ) Instituto de Ciencia de Materiales de Aragon, CSIC-University of Zaragoza, ES-50009 Zaragoza The rapid-solidification processing (by a cooling rate of 105 -1 06 K/s) was used for the preparation of deeply undercooled cryolite/alumina (Na3AlF 6/Al2O3) melts. We found a mass of nanotubes on the surface of these undercooled melts. The nanotubes were preferentially located on the defect places of the surface with the following approximate dimensions: base � 100 � 100 nm, length � 1000 nm. The solidified samples with the nanotubes on the surface were analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and infrared spectroscopy (IR).

In this study we give evidence for the strong dependence of the compositional and magnetic properties on the synthesis conditions of polycrystalline Co 2 (Cr 1− x Fe x )Al Heusler alloys (0 ≤ x ≤ 1) by comparing the properties of as-grown and annealed compounds. Strong chemical inhomogeneities are found at the micrometric level depending on the compound and the synthesis method. Moreover, we find that the Co content is homogeneous at the micrometric level in all the studied samples in sharp contrast with significant inhomogeneous distribution of (Fe/Cr) and Al at the micrometric level, especially for Cr-rich compounds ( x ≤ 0.4). We have found that the magnetic properties (the Curie temperature and the saturation magnetization) are strongly depressed in the annealed compounds with respect to the corresponding as-grown compounds. For the as-grown compounds the saturation magnetization is close to the theoretically predicted one for x ≥ 0.7 whereas it is lower than the theoretically predicted one for x ≤ 0.4, which correlates with the observed chemical inhomogeneity.

We report a study of the magnetotransport properties of the Co2Cr0.6Fe0.4Al Heusler alloy grown by means of the arc-melting technique. X-ray diffraction and energy dispersive X-ray spectroscopy have been used to analyze the crystallographic structure and the sample stoichiometry. Temperature-dependent magnetization measurements have been carried out in the range 300–850 K. Co2Cr0.6Fe0.4Al is theoretically predicted to have full positive spin polarization at the Fermi level, and as a consequence its spin-dependent transport properties are being intensively studied. Low field magnetoresistance exceeding 30% has been observed very recently in Co2Cr0.6Fe0.4Al compact pellets. We have performed magnetoresistance and magnetostriction measurements in both the as-grown alloy and compact pellets made of mechanically milled Co2Cr0.6Fe0.4Al. The as-grown and the milled sample show negligible anisotropic magnetostriction (25 μst at saturation), whilst only the milled sample exhibits magnetoresistance (0.65% at 300 K). These results permit us to discard the magnetostrictive effects as the magnetoresistance source.

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.

arXiv:1410.7782v1, Long-range correlations in two-dimensional (2D) systems are significantly altered by disorder potentials. Theory has predicted the existence of disorder-induced phenomena, such as Anderson localization or the emergence of a Bose glass. More recently, it has been shown that when disorder breaks 2D continuous symmetry, long-range correlations can be enhanced. Experimentally, developments in quantum gases have allowed the observation of the effects of competition between interaction and disorder. However, experiments exploring the effect of symmetry-breaking disorder are lacking. Here, we create a 2D vortex lattice at 0.1 K in a superconducting thin film with a well-defined 1D thickness modulation - the symmetry-breaking disorder - and track the field-induced modification using scanning tunnelling microscopy. We find that the 1D modulation becomes incommensurate with the vortex lattice and drives an order-disorder transition, behaving as a scale-invariant disorder potential. We show that the transition occurs in two steps and is mediated by the proliferation of topological defects. The resulting critical exponents determining the loss of positional and orientational order are far above theoretical expectations for scale-invariant disorder and follow instead the critical behaviour describing dislocation unbinding melting. Our data show that randomness disorders a 2D crystal, with enhanced long-range correlations due to the presence of a 1D modulation., This work was supported by the Spanish MINECO (FIS2011-23488, MAT2011-27553-C02, MAT 2012-38318-C03, Consolider Ingenio Molecular Nanoscience CSD2007-00010), the Comunidad de Madrid through program Nanobiomagnet (S2009/MAT-1726) and by the Marie Curie Actions under the project FP7-PEOPLE-2013-CIG-618321 and contract no. FP7-PEOPLE-2010-IEF-273105.

This work describes the use of focused-ion-beam for the fabrication of metallic nanoconstrictions on a Fe thin film with in situ monitoring of the structure's resistance. With this approach the sequential FIB steps that are used for the gradual narrowing of the nanoconstriction are observed as changes in the measured resistance, thus providing very good control of the milling process. The FIB patterning enables precise termination of the process just before the crossover between the metallic and tunneling regimes near the conductance quantum value G"0 (G"0=2e^2/h). Compared to previous approaches to create nanoconstrictions with focused-ion-beam, this new technique determines precisely the current direction and minimizes Ga damage at the nanoconstriction.

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License. (CC BY-NC-ND 3.0)., We present the magnetic characterization of cobalt wires grown by focused electron beam-induced deposition (FEBID) and studied using static piezoresistive cantilever magnetometry. We have used previously developed high force sensitive submicron-thick silicon piezoresistive cantilevers. High quality polycrystalline cobalt microwires have been grown by FEBID onto the free end of the cantilevers using dual beam equipment. In the presence of an external magnetic field, the magnetic cobalt wires become magnetized, which leads to the magnetic field dependent static deflection of the cantilevers. We show that the piezoresistive signal from the cantilevers, corresponding to a maximum force of about 1 nN, can be measured as a function of the applied magnetic field with a good signal to noise ratio at room temperature. The results highlight the flexibility of the FEBID technique for the growth of magnetic structures on specific substrates, in this case piezoresistive cantilevers, This work was supported by the Spanish Ministry of Economy and Competitiveness through projects No. TEC2011-23600, Nanoselect-CSD2007-00041 (Consolider-Ingenio 2010 programme) and MAT2011- 27553-C02, including FEDER funds, by the Aragón Regional Government, and by the EU Sudoe Interreg TRAIN2 proyect.

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.

The deposition of nanostructures by focused beams, of either electrons or ions, is a novel method of nanofabrication with potential. These deposition techniques, known as focused ion beam induced deposition (FIBID) and focused electron beam induced deposition (FEBID), have been developed in the last 30 years and are now being allocated a large number of scientific and technical resources in order to achieve many goals in the field of nanotechnology.