Soraya Sangiao | University of Zaragoza (original) (raw)

Papers by Soraya Sangiao

Bulletin of the American Physical Society, Mar 15, 2016

Given the high interest in the fabrication and application of carbon-based materials, we present ... more Given the high interest in the fabrication and application of carbon-based materials, we present a new and cost-effective method for the synthesis of graphite oxide nanoplatelets (GONP) using bamboo pyroligneous acid (BPA) as source. GONP-BPA present lateral dimensions of 5-100 micro-meter and thickness less than 80 nm, as confirmed by TEM. EEL spectra show that locally the carbon is mainly in sp 2 bonding configuration and confirm a short/medium range crystalline order. Elemental analysis by EDX confirms the presence of oxygen in an atomic percentage ranging from 17 to 5%. For electrical characterization, single platelets were contacted by focused-ion-beam-induced deposition of Pt nanowires. The four-point probe electrical conductivity shows a direct correlation with the oxygen percentage. Three orders of magnitude conductivity rise is observed by the oxygen reduction, reaching a value of 2.3x10 3 S/m at the final deoxidation degree. The results suggest that GONP-BPA could be used in the development of advanced devices and sensors.

Nanoscale advances, 2021

Emergent technologies are required in the field of nanoelectronics for improved contacts and inte... more Emergent technologies are required in the field of nanoelectronics for improved contacts and interconnects at nano and micro-scale. In this work, we report a highly-efficient nanolithography process for the growth of cobalt nanostructures requiring an ultra-low charge dose (15 mC cm À2 , unprecedented in single-step charge-based nanopatterning). This resist-free process consists in the condensation of a $28 nm-thick Co 2 (CO) 8 layer on a substrate held at À100 C, its irradiation with a Ga + focused ion beam, and substrate heating up to room temperature. The resulting cobalt-based deposits exhibit sub-100 nm lateral resolution, display metallic behaviour (room-temperature resistivity of 200 mU cm), present ferromagnetic properties (magnetization at room temperature of 400 emu cm À3) and can be grown in large areas. To put these results in perspective, similar properties can be achieved by room-temperature focused ion beam induced deposition and the same precursor only if a 2 Â 10 3 times higher charge dose is used. We demonstrate the application of such an ultra-fast growth process to directly create electrical contacts onto graphene ribbons, opening the route for a broad application of this technology to any 2D material. In addition, the application of these cryo-deposits for hard masking is demonstrated, confirming its structural functionality.

Nanotechnology, Jan 16, 2016

We demonstrate that the spectral location of extraordinary optical transmission (EOT) resonances ... more We demonstrate that the spectral location of extraordinary optical transmission (EOT) resonances in metallic arrays of rectangular holes can be plasmonically tuned in the near and mid-infrared ranges. The experiments have been performed on patterned gold films. We focus on a subset of localized resonances occurring close to the cut-off wavelength of the holes, λ c. Metals are usually regarded as perfect electric conductors in the infrared regime, with an EOT cut-off resonance found around λ c = 2 L for rectangular holes (L being the long edge). For real metals, the penetration of the electromagnetic fields is simply seen as effectively enlarging L. However, by changing the hole short edge, we have found that λ c varies due to the excitation of gap surface plasmon polaritons. Finite-element calculations confirm that in these high aspect ratio rectangles with short edges two important aspects have to be taken into account in order to explain the experiments: the finite conductivity of...

Materials

Focused Ion Beam patterning has become a widely applied technique in the last few decades in the ... more Focused Ion Beam patterning has become a widely applied technique in the last few decades in the micro- and nanofabrication of quantum materials, representing an important advantage in terms of resolution and versatility. However, ion irradiation can trigger undesired effects on the target material, most of them related to the damage created by the impinging ions that can severely affect the crystallinity of the sample, compromising the application of Focused Ion Beam to the fabrication of micro- and nanosized systems. We focus here on the case of Bi2Se3, a topological material whose unique properties rely on its crystallinity. In order to study the effects of ion irradiation on the structure of Bi2Se3, we irradiated with Ga+ ions the full width of Hall-bar devices made from thin films of this material, with the purpose of inducing changes in the electrical resistance and characterizing the damage created during the process. The results indicate that a relatively high ion dose is ne...

Nanoscale Advances

NanoSQUIDs are quantum sensors that excel in detecting a change in magnetic flux with high sensit... more NanoSQUIDs are quantum sensors that excel in detecting a change in magnetic flux with high sensitivity and high spatial resolution. Here, we employ Ga+ focused ion beam induced deposition techniques to grow W–C nanoSQUIDs and we investigate their electrical response.

Open Research Europe

Background: The use of a focused ion beam to decompose a precursor gas and produce a metallic dep... more Background: The use of a focused ion beam to decompose a precursor gas and produce a metallic deposit is a widespread nanolithographic technique named focused ion beam induced deposition (FIBID). However, such an approach is unsuitable if the sample under study is sensitive to the somewhat aggressive exposure to the ion beam, which induces the effects of surface amorphization, local milling, and ion implantation, among others. An alternative strategy is that of focused electron beam induced deposition (FEBID), which makes use of a focused electron beam instead, and in general yields deposits with much lower metallic content than their FIBID counterparts. Methods: In this work, we optimize the deposition of tungsten-carbon (W-C) nanowires by FEBID to be used as electrical contacts by assessing the impact of the deposition parameters during growth, evaluating their chemical composition, and investigating their electrical response. Results: Under the optimized irradiation conditions, t...

Journal of Solid State Chemistry

ACS Applied Materials & Interfaces

Metallic nanopatterns are ubiquitous in applications that exploit the electrical conduction at th... more Metallic nanopatterns are ubiquitous in applications that exploit the electrical conduction at the nanoscale, including interconnects, electrical nanocontacts, and small gaps between metallic pads. These metallic nanopatterns can be designed to show additional physical properties (optical transparency, plasmonic effects, ferromagnetism, superconductivity, heat evacuation, etc.). For these reasons, an intense search for novel lithography methods using uncomplicated processes represents a key ongoing issue in the achievement of metallic nanopatterns with high resolution and high throughput. In this contribution, we introduce a simple methodology for the efficient decomposition of Pd 3 (OAc) 6 spin-coated thin films by means of a focused Ga + beam, which results in metallic-enriched Pd nanostructures. Remarkably, the usage of a charge dose as low as 30 μC/cm 2 is sufficient to fabricate structures with a metallic Pd content above 50% (at.) exhibiting low electrical resistivity (70 μΩ• cm). Binary-collision-approximation simulations provide theoretical support to this experimental finding. Such notable behavior is used to provide three proof-of-concept applications: (i) creation of electrical contacts to nanowires, (ii) fabrication of small (40 nm) gaps between large metallic contact pads, and (iii) fabrication of large-area metallic meshes. The impact across several fields of the direct decomposition of spin-coated organometallic films by focused ion beams is discussed.

Nanomaterials

Since its discovery in 1911, superconductivity has represented an equally inciting and fascinatin... more Since its discovery in 1911, superconductivity has represented an equally inciting and fascinating field of study in several areas of physics and materials science, ranging from its most fundamental theoretical understanding, to its practical application in different areas of engineering. The fabrication of superconducting materials can be downsized to the nanoscale by means of Focused Ion/Electron Beam Induced Deposition: nanopatterning techniques that make use of a focused beam of ions or electrons to decompose a gaseous precursor in a single step. Overcoming the need to use a resist, these approaches allow for targeted, highly-flexible nanopatterning of nanostructures with lateral resolution in the range of 10 nm to 30 nm. In this review, the fundamentals of these nanofabrication techniques are presented, followed by a literature revision on the published work that makes use of them to grow superconducting materials, the most remarkable of which are based on tungsten, niobium, mo...

One current goal of spintronics is the development of sustainable information technology based on... more One current goal of spintronics is the development of sustainable information technology based on pure spin currents. One promising way to do this is to use spin waves (SWs) in low damping insulating ferrimagnets like yttrium iron garnet (YIG) where relaxation can be controlled by spin orbit torque (SOT) at a heavy metal interface [1]. However, such metal/insulator hybrid devices exhibit saturation of SW amplification due to nonlinear coupling between modes [2].<br/>Two strategies can be considered to overcome these issues. i) Nanopatterning leads to quantization of SW modes [3], thereby limiting the available nonlinear processes [4]. ii) Tuning the perpendicular magnetic anisotropy (PMA) can be used to control the sign of the nonlinear frequency shift [5]. Recently, the growth of ultra-thin films of bismuth doped YIG (BiYIG) with tunable PMA has been achieved [6], resulting in greatly improved characteristics of SOT emitted SWs [7].<br/>Here, we study the magnetization ...

Here, we will show the application of Cryo-FIBID to other precursors beyond W(CO)6, with the aim ... more Here, we will show the application of Cryo-FIBID to other precursors beyond W(CO)6, with the aim of obtaining ultrafast growth of metallic deposits, and eventually additional functional properties. In particular, we will discuss the results obtained using the (CH3)3Pt(CpCH3) precursor, which is commonly found in commercial FIB equipment.

Cornell University - arXiv, Mar 10, 2022

NanoSQUIDs are quantum sensors that excel in detecting a small change in magnetic flux with high ... more NanoSQUIDs are quantum sensors that excel in detecting a small change in magnetic flux with high sensitivity and high spatial resolution. Here, we employ resist-free direct-write Ga + Focused Ion Beam Induced Deposition (FIBID) techniques to grow W-C nanoSQUIDs, and we investigate their electrical response to changes in the magnetic flux. Remarkably, FIBID allows the fast (3 min) growth of 700 nm×300 nm Dayem-bridge nanoSQUIDs based on narrow nanowires (50 nm wide) that act as Josephson junctions. The observed transfer coefficient (output voltage to magnetic flux change) is very high (up to 1301 µ V/Φ0), which correlates with the high resistivity of W-C in the normal state. We discuss here the potential of this approach to reduce the active area of the nanoSQUIDs to gain spatial resolution as well as their integration on cantilevers for scanning-SQUID applications.

Nanotechnology, 2022

The ability to create metallic patterned nanostructures with excellent control of size, shape and... more The ability to create metallic patterned nanostructures with excellent control of size, shape and spatial orientation is of utmost importance in the construction of next-generation electronic and optical devices as well as in other applications such as (bio)sensors, reactive surfaces for catalysis, etc. Moreover, development of simple, rapid and low-cost fabrication processes of metallic patterned nanostructures is a challenging issue for the incorporation of such devices in real market applications. In this contribution, a direct-write method that results in highly conducting palladium-based nanopatterned structures without the need of applying subsequent curing processes is presented. Spin-coated films of palladium acetate were irradiated with an electron beam to produce palladium nanodeposits (PdNDs) with controlled size, shape and height. The use of different electron doses was investigated and its influence on the PdNDs features determined, namely: (1) thickness of the deposits...

Nanomaterials, 2021

Topological insulators are materials with time-reversal symmetric states of matter in which an in... more Topological insulators are materials with time-reversal symmetric states of matter in which an insulating bulk is surrounded by protected Dirac-like edge or surface states. Among topological insulators, Bi2Se3 has attracted special attention due to its simple surface band structure and its relatively large band gap that should enhance the contribution of its surface to transport, which is usually masked by the appearance of defects. In order to avoid this difficulty, several features characteristic of topological insulators in the quantum regime, such as the weak-antilocalization effect, can be explored through magnetotransport experiments carried out on thin films of this material. Here, we review the existing literature on the magnetotransport properties of Bi2Se3 thin films, paying thorough attention to the weak-antilocalization effect, which is omnipresent no matter the film quality. We carefully follow the different situations found in reported experiments, from the most ideal ...

Nanoscale Advances, 2021

Direct electrical contacts (no resist is involved) have been grown on graphene ribbons by the Cry... more Direct electrical contacts (no resist is involved) have been grown on graphene ribbons by the Cryo-FIBID technique for the first time, opening the route for a wider use on other 2D materials.

ACS Nano, 2015

The successful application of focused electron (and ion) beam induced deposition techniques for t... more The successful application of focused electron (and ion) beam induced deposition techniques for the growth of nanowires on flexible and transparent polycarbonate films is reported here. After minimization of charging effects in the substrate, sub-100 nm-wide Pt, W, and Co nanowires have been grown and their electrical conduction is similar compared to the use of standard Sibased substrates. Experiments where the substrate is bent in a controlled way indicate that the electrical conduction is stable up to high bending angles, >50°, for low-resistivity Pt nanowires grown by the ion beam. On the other hand, the resistance of Pt nanowires grown by the electron beam changes significantly and reversibly with the bending angle. Aided by the substrate transparency, a diffraction grating in transmission mode has been built based on the growth of an array of Pt nanowires that shows sharp diffraction spots. The set of results supports the large potential of focused beam deposition as a high-resolution nanolithography technique on transparent and flexible substrates. The most promising applications are expected in flexible nano-optics and nanoplasmonics, flexible electronics, and nanosensing.

Physical Review Letters, 2013

Physical Review B, 2011

We study the magnetic-field dependence of the conductance in planar ferromagnet-superconductor na... more We study the magnetic-field dependence of the conductance in planar ferromagnet-superconductor nanocontacts created with focused-electron/ion-beam techniques. From the fits of the differential conductance curves in high magnetic fields, we obtain the magnetic field dependences of the superconducting gap and the broadening parameter. Orbital depairing is found to be linear with magnetic field. We evaluate the magnetic field dependence of the quasiparticle density of states, and we compare it with the value obtained by scanning tunneling spectroscopy experiments.

Applied Physics Letters, 2010

We study the electrical resistivity of individual Bi nanowires of diameter 100 nm fabricated by e... more 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.