Alumina Barrier Layer Research Articles

Healing Donor Defect States in CVD-Grown MoS2 Field-Effect Transistors Using Oxygen Plasma with a Channel-Protecting Barrier.

Molybdenum disulfide (MoS2 ), a metal dichalcogenide, is a promising channel material for highly integrated scalable transistors. However, intrinsic donor defect states, such as sulfur vacancies (Vs ), can degrade the channel properties and lead to undesired n-doping. A method for healing the donor defect states in monolayer MoS2 is proposed using oxygen plasma, with an aluminum oxide (Al2 O3 ) barrier layer that protects the MoS2 channel from damage by plasma treatment. Successful healing of donor defect states in MoS2 by oxygen atoms, even in the presence of an Al2 O3 barrier layer, is confirmed by X-ray photoelectron spectroscopy, photoluminescence, and Raman spectroscopy. Despite the decrease in 2D sheet carrier concentration (Δn2D = -3.82×1012 cm-2 ), the proposed approach increases the on-current and mobility by 18% and 44% under optimal conditions, respectively. Metal-insulator transition occurs at electron concentrations of 5.7×1012 cm-2 and reflects improved channel quality. Finally, the activation energy (Ea ) reduces at all the gate voltages (VG ) owing to a decrease in Vs , which act as a localized state after the oxygen plasma treatment. This study demonstrates the feasibility of plasma-assisted healing of defects in 2D materials and electrical property enhancement and paves the way for the development of next-generation electronic devices.

Developing a Novel Growth Method for Carbon-Infiltrated Carbon Nanotubes on Ti6Al4V

Carbon-infiltrated carbon nanotubes (CICNT) are cylindrical rolls of pure carbon atoms with a honeycomb molecular structure. They have specific applications in medical implants due to their biofilm resistance properties. CICNT can be grown on a variety of material substrates such as silicon, stainless steel, and pure titanium. Different substrates require different CICNT growth processes. This study developed a growth method for CICNT on Ti6Al4V, a titanium alloy commonly used as a medical implant material due to its strong mechanical properties and excellent biocompatibility. However, due to the presence of vanadium in the alloy, it is difficult to use it as a substrate for CICNT growth. To solve this problem, this study used an indirect growth method, which placed a barrier layer of alumina (Al2O3) between the Ti6Al4V and an iron growth catalyst layer. A control group was also created without an alumina barrier layer. This study additionally investigated the differences between two deposition methods: electron-beam physical vapor deposition (PVD) and atomic layer deposition (ALD). After CICNT growth, the samples showed that the deposition of the barrier layer allowed the growth of CICNT on Ti6Al4V. Using a scanning electron microscope (SEM), the results also showed that at the levels of alumina studied, the deposition method did not make a difference to CICNT coverage of the Ti6Al4V. These results illustrate the fact that Ti6Al4V can be used as a substrate for CICNT if a barrier layer is used.

Алюмооксидные нанопористые мембраны как основа функциональных нанокомпозитных материалов

In the present study, we report about results of obtaining nanocomposite materials based on various types of nanoporous alumina membranes (NAM). The NAM were fabricated by two ways: (I) — using the technique of thinning the barrier layer of porous anodic alumina; (2) — by two-layer galvanostatic electrochemical anodization of aluminium samples. Using atomic force microscopy, it was found that a method of thermal decomposition of K2MnO4 leads to the formation of nanoparticles γ-MnO2 with size ~ 20 nm on the surface and in the pores of NAM, and the use of the method of photochemical synthesis of Ag nanoparticles with a size of ~ 30 nm.

Effect of Al plating on growth behavior of TGO layer in CoCrNiAlY–YSZ–RSZ dual-ceramic coating

Thermally grown oxides (TGO) are the key to determine the longevity of thermal barrier coatings (TBCs). This study investigates the growth behavior of the TGO layer in a dual-ceramic coating consisting of CoCrNiAlY, yttria-stabilized zirconia, and rare earth-stabilized zirconia (CoCrNiAlY–YSZ–RSZ) with an Al plating layer. The results demonstrate that these inherent defects (e.g., holes or cracks) in the dual-ceramic layer without Al plating provide diffusion channels for oxygen. These diffusion channels lead to a high oxidation weight gain rate, severe CoCrNiAlY elemental diffusion, and rapid TGO growth. However, the use of Al plating layer effectively seals these inherent ceramic layer defects and leads to the formation of a dense and continuous alumina barrier layer. This barrier layer significantly inhibits internal oxygen diffusion as well as rapid TGO growth. Therefore, the dual-ceramic coating fabricated with Al plating layer exhibits an extremely low oxidation weight gain rate compared to the coating without Al plating.

Nanoporous anodic alumina with ohmic contact between substrate and infill: Application to perovskite solar cells

AbstractThe use of a nanostructured aluminum substrate as the cathode for a perovskite photovoltaic device is described. This cathode consists of an aluminum substrate onto which a highly ordered array of aluminum oxide tubular pores was grown via anodization. The 1‐μm thick pores – arranged in a closed‐packed hexagonal pattern – were subsequently selectively etched at the bottom to remove the so‐called aluminum oxide barrier layer. The subsequent infiltration of the pores with the components of a methylammonium lead iodide perovskite solar cells, and the completion with a semi‐transparent anode, have shown to allow the establishment of an ohmic contact between the substrate itself and the components infiltrated into the Al2O3 pores. Indeed, a clear rectifying behavior was observed on the full devices, as well as modest photovoltaic conversion efficiencies. This paper demonstrates that an ohmic contact can be established between the aluminum substrate from which nanoporous anodic alumina was grown, and that the pores can be used to compartmentalize the infill material down to the nanoscopic level.

The growth and unique electronic properties of the porous-alumina-assisted hafnium-oxide nanostructured films

Hafnium-oxide nanostructures of controlled composition and properties are in demand for modern electronic and optical engineering. Here hafnium-oxide nanostructured films are synthesized on substrates via the anodizing/re-anodizing of a thin Hf layer through a porous anodic alumina (PAA) film at 150/400 V in 0.2 m H3PO4 electrolyte and examined by SEM, EIS, and Mott-Schottky analysis. The films are composed of HfOx nanorods, which grow in the pores, anchored to a continuous HfO2 bottom layer by tiny HfOx nanoroots penetrating the alumina barrier layer. The understanding of film nucleation and growth is advanced through disclosing the hidden features and field-assisted modifications of the metal-oxide interfaces, such as O2-filled nanosized voids and individual hafnium-oxide nanoroots dominating within the alumina barrier layer and securing electron transport to each nanorod. The films reveal a unique combination of electrical properties, such that the bottom oxide behaves like an ideal dielectric whereas the roots and rods show semiconducting behavior. A 600 °C annealing at atmospheric pressure surprisingly leaves the rods and roots semiconducting and still amorphous while the annealing at 10−5 Pa transforms the entire film to a nanocrystallite-containing n-type semiconductor, of a high doping density of up to 2 1021 cm−3. Further anodic polarization of the PAA-free vacuum-annealed film generates dielectric anodic oxide over the film, of thickness proportional to applied potential until the thinner roots and finally the dominating root become fully blocked for electron conduction. Potential applications include high-k dielectrics for high-voltage electrolytic capacitors, semiconducting active layers for gas sensing, or photoanodes for photoelectrochemical water splitting.

Extreme Heating of Alumina Barrier Layer During High Electric Field Anodization of Aluminum

The temperature of alumina barrier layer during a high electric field anodization of aluminum (the current density more than 50[Formula: see text]mA/cm[Formula: see text] has been studied by analyzing the aluminum film resistance. In the case of Joule heat power density to be larger than 20[Formula: see text]W/cm2, the temperature inside the barrier layer can exceed [Formula: see text]C, which leads to the local melting of aluminum. Scanning electron microscopy has shown the location of molten aluminum droplets and their movement during the anodization process.

On-substrate porous-anodic-alumina-assisted gold nanostructure arrays: Meeting the challenges of various sizes and interfaces

Arrays of 0- and 1-dimensional noble-metal nanostructures aligned on solid substrates are in demand for nanocatalysis, bio- and optical sensing, or biomolecular analysis. Here we introduce a range of advances based on a systematic research towards the porous-anodic-alumina (PAA)-assisted on-substrate arrays of gold nanostructures, such as rods and spheres, spatially-separated and highly aligned on a metal or semiconductor supporting layer via a blend of the anodizing, re-anodizing, and post-anodizing treatments applied to a thin layer of Al superimposed on selected valve metals (W, Ti, Hf), metal bilayers (W/Ti), or binary metal alloy layers (W-Ti). The achievements are due to (1) the improved self-organization in the PAA thin films during the self-localizing high-current anodization of the upper Al layer at challenging potentials ranging 100–250 V and 20 to 5 V, and (2) the enhanced penetration of the alumina barrier layer by the undergrowing metal oxide due to the increasing polarization (re-anodizing). The protrusions of the undergrown metal oxide can be either selectively dissolved away providing perfect nanoholes in the alumina barrier layer or left as formed in the barrier layer and annealed in vacuum to increase their electron conductance and serve as the supports for subsequent metal electrodeposition. Additionally, the in-situ amplitude-modulated constant-current pulse deposition mode combined with the original surface-wiping technique to remove the overdeposited gold allow for smooth nucleation and uniform finishing of perfect arrays of on-substrate gold nanospheres and nanorods, having diameters from 10 to over 250 nm and length up to 2.5 μm.

Influence of nitrogen species on the porous-alumina-assisted growth of TiO2 nanocolumn arrays

Porous-anodic-alumina (PAA)-assisted anodizing in oxalic acid electrolytes combined with re-anodizing to a more anodic potential of a titanium layer on substrate, followed by chemical dissolution of the PAA overlayer result in TiO2 nanocolumn arrays, which may however be chemically unstable and destroy during the PAA dissolution. Here we show that this is because the TiO2 nanocolumns have easy-to-dissolve alumina-titania mixed-oxide ‘nanoroots’ penetrating the alumina barrier layer, where gas nano-bubbles and voids form respectively inside and between the titania roots, owing to the field-assisted crystallization of the bottom titanium oxide. The problem is solved by alloying nitrogen with titanium in the precursor film, with a compositional spread of nitrogen from 2 to 50 at%, to grow differently N-doped TiO2 nanocolumn arrays via the PAA-assisted anodizing in oxalic acid at 40 V followed by re-anodizing up to 240 V. The stability of such arrays increases with increasing nitrogen content, reaching an ideal 100% level for the Ti–50 at%N alloy films. The effect is proved to be due to the incorporation of nitrogen into the columns and roots with formation of oxynitride, which increases their chemical resistance and effectively suppresses the field-assisted crystallization of titania, leading to the obstructed O2 evolution, smaller bubbles and voids, less mixing of the two oxides in the roots, and thickening and merging the roots. A model is developed of the oxide growth and dissolution, explaining the instability of the pure TiO2 nanocolumn arrays and defining the stabilizing effect of the nitrogen species. The doping with nitrogen may make the TiO2 nanocolumn arrays highly appropriate for applications to photocatalysis and energy conversion.

The effect of barrier layer conditions on the electrodeposition efficiency and magnetic properties of Fe nanowire arrays

Fabrication of different nanostructures based on template-assisted methods has become conventional, due to their numerous potential applications. In this paper, Fe nanowire arrays (NWAs) were fabricated using a pulsed electrodeposition in porous anodic alumina (PAA) templates. The effect of alumina barrier layer conditions such as barrier layer temperature (BLT) and Cu pre-plating at the dendritic sections of pores on the electrodeposition efficiency (EE) and magnetic properties of Fe NWAs in two pH regimes (2.6 and 4.0) has been investigated. At pH 4.0, BLT was changed from ~ 4 to ~ 32 °C, leading to an EE of approximately 60% for BLT ~ 24 °C. Moreover, to overcome the problem of low EE ~ 2% at the pH of 2.6, Cu pre-plating was performed with deposition current densities of 25 and 35 mA/cm2. This procedure increased the EE up to about 40%, providing a promising approach to enhance the EE in the fabrication of Fe NWAs. Furthermore, a nearly constant trend of magnetic properties was observed for highly crystalline Fe NWs.

Detection of Odontoglossum Ringspot Virus Infected Phalaenopsis Using a Nano-Structured Biosensor

In this study, a highly sensitive biosensor based on a 3D nano-structured sensing electrode made from an anodic aluminum oxide (AAO) barrier layer with the uniform distribution of gold nanoparticles (GNPs) is proposed for label-free detection of orchid viruses. This nanostructured electrode was utilized for developing a label-free sensing system based on electrochemical impedance spectroscopy (EIS) to directly detect the Odontoglossum ringspot virus (ORSV) concentration from orchid leaves. The ORSV antibody (anti-ORSV) was employed as a detecting probe and was covalently immobilized on the nanostructured sensing electrode surface through a self-assembled monolayer (SAM) method. Through a selective binding interaction between specific antigen and antibody pairs, our nanostructured biosensors can provide a high specificity and accuracy sensing result. Our experimental results revealed that the specific binding of ORSV onto the immobilized anti-ORSV gave rise to the incremental interfacial charge transfer resistance of the electrode, allowing one to distinguish between healthy and infected orchids in a fast and accurate manner. The linear detection range is 50,000 ng/mL–0.5 ng/mL with R2 = 0.9686. A detection limit of 0.345 ng/mL can be achieved. These results demonstrated that our ORSV biosensor is feasible for field applications.

Characterisation of Ceramic-Coated 316LN Stainless Steel Exposed to High-Temperature Thermite Melt and Molten Sodium

Currently, stainless steel grade 316LN is the material of construction widely used for core catcher of sodium-cooled fast reactors. Design philosophy for core catcher demands its capability to withstand corium loading from whole core melt accidents. Towards this, two ceramic coatings were investigated for its application as a layer of sacrificial material on the top of core catcher to enhance its capability. Plasma-sprayed thermal barrier layer of alumina and partially stabilised zirconia (PSZ) with an intermediate bond coat of NiCrAlY are selected as candidate material and deposited over 316LN SS substrates and were tested for their suitability as thermal barrier layer for core catcher. Coated specimens were exposed to high-temperature thermite melt to simulate impingement of molten corium. Sodium compatibility of alumina and PSZ coatings were also investigated by exposing samples to molten sodium at 400 °C for 500 h. The surface morphology of high-temperature thermite melt-exposed samples and sodium-exposed samples was examined using scanning electron microscope. Phase identification of the exposed samples was carried out by x-ray diffraction technique. Observation from sodium exposure tests indicated that alumina coating offers better protection compared to PSZ coating. However, PSZ coating provided better protection against high-temperature melt exposure, as confirmed during thermite melt exposure test.

Effect of Electric Field Strength on Barrier Layer Thickness and Anion Incorporation of Anodic Porous Alumina

Anodic porous alumina films having a closely packed hexagonal array of cells have attracted much attention as a starting material in the fabrication of nano-devices because of the high controllability of porous structures (e.g., cell size, pore size, pore interval, and pore depth) on dimensions ranging from the submicron to nanometer range. In recent years, the mechanism of self-ordering of cell arrangement of anodic porous alumina has been intensely studied. We proposed anodizing under high electric field strength as a key factor for self-ordering of cell arrangement [1, 2]. However, only a few reports are found on the irregularities of barrier layer thickness and morphology of each cell of anodic porous alumina. In this study, we evaluated the influence of electrolytic factors (e.g., current density, applied voltage, and anodizing time) on cell morphology of anodic porous alumina. Especially, we focused on the effect of the electric field strength on the barrier layer thickness and anion incorporation behavior. High purity aluminum sheets were anodized in typical electrolytes of sulfuric acid, oxalic acid, and phosphoric acid at different voltage. After detachment of the porous alumina films from the substrate in saturated mercuric chloride solution, the specimens were immersed in phosphoric acid to dissolve the barrier layer from the backside. By SEM observation of structural change of the cells during chemical etching, the homogeneity of the barrier layer thickness could be evaluated. Although the thickness of the barrier layer of porous alumina formed at constant voltage has been believed to be uniform, we confirmed that the thickness of the barrier layer of each cell was not uniform; the thickness of the barrier layer of the smaller cells was thinner than that of the larger cells. Concerning anion incorporation behavior, we evaluated the depth of anion incorporation into the cell wall by the difference in the strength of contrast of the SEM image of rear surface of porous alumina films because the dissolution rate of the anion-free layer was slower than that of the anion-incorporated layer. The details of the thickness inhomogeneity of the barrier layer and anion incorporation behavior will be discussed from a standpoint of the high field theory.

Rapid thermal annealing effect on the microstructural and optical properties of nc-Si embedded in porous anodic alumina

Abstract In this work, nanocrystalline silicon (nc-Si) are deposited in a porous anodic alumina (PAA) matrix by a radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) method. The rapid thermal annealing (RTA) effect on morphological and microstructural properties of nc-Si/PAA structure is investigated by SEM, EDX, XRD technique and Raman spectroscopy. Crystallization of the amorphous silicon is obtained after annealing at was 550 °C during a time ranging from 10 to 120 min. The effect of thermal annealing on the optical properties of nc-Si/PAA structure was studied by Spectroscopic Ellipsometry (SE) in the spectral range 0.3–0.8 μm. The Ellipsometric analysis demonstrated the formation of two separate layers during the annealing process. A silicon/alumina alloy as the upper layer and a polysilicon film at the bottom and in contact with the alumina barrier layer. The optical constants, thickness and the composition of each film have been estimated from the SE data using Bruggeman effective medium approximation (BEMA). PL spectroscopy was used to investigate the bandgap energy of nc-Si embedded within the PAA matrix, the origin of emission PL spectra as well as the observed red-shift have been discussed.

Magnetic alloy nanowire arrays with different lengths: Insights into the crossover angle of magnetization reversal process

Nanoscale magnetic alloy wires are being actively investigated, providing fundamental insights into tuning properties in magnetic data storage and processing technologies. However, previous studies give trivial information about the crossover angle of magnetization reversal process in alloy nanowires (NWs). Here, magnetic alloy NW arrays with different compositions, composed of Fe, Co and Ni have been electrochemically deposited into hard-anodic aluminum oxide templates with a pore diameter of approximately 150nm. Under optimized conditions of alumina barrier layer and deposition bath concentrations, the resulting alloy NWs with aspect ratio and saturation magnetization (Ms) up to 550 and 1900emucm−3, respectively, are systematically investigated in terms of composition, crystalline structure and magnetic properties. Using angular dependence of coercivity extracted from hysteresis loops, the reversal processes are evaluated, indicating non-monotonic behavior. The crossover angle (θc) is found to depend on NW length and Ms. At a constant Ms, increasing NW length decreases θc, thereby decreasing the involvement of vortex mode during the magnetization reversal process. On the other hand, decreasing Ms decreases θc in large aspect ratio (>300) alloy NWs. Phenomenologically, it is newly found that increasing Ni content in the composition decreases θc. The angular first-order reversal curve (AFORC) measurements including the irreversibility of magnetization are also investigated to gain a more detailed insight into θc.

A template/electrochemical deposition method for fabricating silver nanorod arrays based on porous anodic alumina

A template/electrochemical deposition method for fabricating silver nanorod arrays based on porous anodic alumina was presented. The barrier layer of porous anodic alumina templates was thinned by step-by-step voltage decrement method. Subsequently, silver ions were reduced into the channels of porous anodic alumina templates by electrochemical deposition method. Electrochemical impedance spectroscopy was utilized for analyzing the thickness of barrier layer of porous anodic alumina templates; the elementary composition and the size of silver nanorod arrays were characterized by X-ray diffraction and field-emission scanning electron microscope, respectively. Experimental results showed that the thickness of barrier layer of porous anodic alumina was suitable for alternating current electrochemical deposition, when anodizing potential was decreased to 70 V and widening time of porous anodic alumina in H3PO4 solution is 80 min. And the silver particles could be deposited into the channels of porous anodic alumina templates at 11 V, 13 V, and 15 V. Different sizes of silver nanorod arrays were obtained by controlling the deposition time. The average diameter of silver nanorod is in the range from 346 nm to 351 nm which is almost consistent with the pore diameter of porous anodic alumina templates (367 nm). The uniform silver nanorod arrays have a considerable potential in the flexible and wearable electronic devices, optics, solar cell, the catalytical electrode, and so on.

Photo- and electroluminescence properties of lanthanide tungstate-doped porous anodic aluminum oxide

A new cathode material for the potential use in light-emitting devices, based on porous anodic alumina (PAA), aluminum and ITO layers has been synthesized. Porous alumina samples with ordered pore arrays were prepared electrochemically from high purity Al sheet in H2SO4 and H3PO4. To be able to apply the matrix obtained in the electroluminescence cell, the thickness of the barrier layer of aluminum oxide was decreased by slow reduction of the anodization voltage to zero. The luminescence and electroluminescence (EL) properties of the Al2O3 matrix admixtured with Eu3+ and Tb3+ ions as well as europium and terbium tungstates, were determined. The particles of inorganic luminophore were synthesized on the walls of the matrix cylindrical nanopores in the two-step process of immersion in solutions of TbCl3 or EuCl3 and Na2WO4. The effect of the nanopores diameter and the thickness of the porous Al2O3 layer on the intensity and relative yield of electroluminescence was analyzed, the best results were obtained for 80–90 µm PAA layers with 140 nm nanopores.

CVD diamond coating on WC-Co substrate with Al-based interlayer

Diamond coating with sufficient adhesion on WC-Co cutting tools is expected to significantly increase their cutting performance. In order to enhance the coating-substrate interfacial adhesion, Al2O3 and Ta mono-interlayer, Al-Al2O3, Al-AlN and Al-Ta duplex interlayer systems have been developed in this study. These interlayer materials were prepared using a magnetron sputtering method, and diamond coating were deposited on them using microwave plasma enhanced chemical vapor deposition. Grazing incident X-ray diffraction was carried out to determine the phase components in the Al-Al2O3 and Al-AlN interlayers. Raman spectroscopy and scanning electron microscopy were used to evaluate the quality, morphology and microstructure of the deposited diamond coatings. Rockwell C indentation testing was performed to evaluate the adhesion of the coatings. To elucidate the coating failure mechanism, the compositions around the delaminated spots of diamond coatings after indentation were identified by Energy-dispersive X-ray spectroscopy. The results show that continuous diamond coatings were achieved on Al2O3, Al-Al2O3, Al-AlN and Al-Ta interlayered substrates, whereas a graphite layer was still formed with the Ta monolayer accompanied by an easy spallation of diamond coatings. The Al interlayer has played an important role in obtaining high purity diamond by in-situ forming an alumina barrier layer. Especially, the diamond coating deposited with an Al-AlN interlayer demonstrates superior interfacial adhesion in comparison with all the other interlayers.

Optimized Porous Anodic Alumina Membranes for Water Ultrafiltration of Pathogenic Bacteria (E. coli).

In this paper, we present the optimization of porous anodic alumina membranes for ultrafiltration prepared by anodically oxidized aluminum foils. The membranes were characterized by field-emission scanning electron microscopy to measure the pore diameter and the membrane thicknesses. The liquid fluxes were estimated through gas permeability measurements using Darcy's and Forchheimerś equations. A 2(3) factorial design we used to optimize the membrane properties: pore diameter, membrane thickness, and liquid flux using as control variables the applied current density, solution composition and concentration. It was observed that the most import variables to control the pore diameter were current density and electrolyte composition. After the anodization both, metallic aluminum substrate and the barrier layer of alumina were removed using adequate solutions to obtain the free standing membrane. Then, Escherichia coli a common bacterial contamination of drinking water was removed using these PAA membranes with 100% of efficiency to obtain bacteria-free water.

Electrochemical pore filling strategy for controlled growth of magnetic and metallic nanowire arrays with large area uniformity

While a variety of template-based strategies have been developed in the fabrication of nanowires (NWs), a uniform pore filling across the template still poses a major challenge. Here, we present a large area controlled pore filling strategy in the reproducible fabrication of various magnetic and metallic NW arrays, embedded inside anodic aluminum oxide templates. Using a diffusive pulsed electrodeposition (DPED) technique, this versatile strategy relies on the optimized filling of branched nanopores at the bottom of templates with Cu. Serving the Cu filled nanopores as appropriate nucleation sites, the DPED is followed by a uniform and homogeneous deposition of magnetic (Ni and Fe) and metallic (Cu and Zn) NWs at a current density of 50 mA cm−2 for an optimal thickness of alumina barrier layer (∼18 nm). Our strategy provides large area uniformity (exceeding 400 μm2) in the fabrication of 16 μm long free-standing NW arrays. Using hysteresis loop measurements and scanning electron microscopy images, the electrodeposition efficiency (EE) and pore filling percentage (Fp) are evaluated, leading to maximum EE and Fp values of 91% and 95% for Ni and Zn, respectively. Moreover, the resulting NW arrays are found to be highly crystalline. Accordingly, the DPED technique is capable of cheaply and efficiently controlling NW growth over a large area, providing a tool for various nanoscale applications including biomedical devices, electronics, photonics, magnetic storage medium and nanomagnet computing.