The main objective of the Ultra-ID Project is to study the fundamental size limits, when the electron transport in one-dimensional (1D) systems can be considered qualitatively similar to macroscopic regime, and to explore qualitatively new phenomena appearing below the certain scale. Project will focus on fabrication, theoretical and experimental study of electron transport in the state-of-the-art narrow 1D objects: normal metals, superconductors, semiconducting heterojunctions and carbon nanotubes. Principal technological objective of the Project is to elaborate old and develop new methods of microfabrication, pushing the reproducible limit of 1D object fabrication down to ~ 10 nm scale. Three independent, but complimentary methods will be used for fabrication of metallic systems: high- resolution e-beam lithography, electrochemical growth of ultra thin nanowires, and progressive reduction of the effective diameter of pre-fabricated 1D objects by plasma etching. Principal technological objective related to activity with 1D semiconductors is the fabrication of high-quality systems enabling application of external potential. Main technological objective related to electron properties of carbon nanotubes is the fabrication of structures suspended on top of a terraced plane or a cleaved edge of superlattice. Research activity with normal electron transport will be concentrated at three main topics: metal- insulator transition in ultra-thin wires, electron decoherence in 1D limit, peculiarities of electron transport in 1D systems with controlled external periodic potential. Study of superconductors will be focused on the problem of quantum phase slips in ultra-thin 1D systems (wires and rings). Experimental part of the scientific activity will include state-of-the-art low noise transport and magnetic measurements at ultra-low temperatures. Theoretical investigation will use modern methods of quantum solid state physics.

I plan to grow nanometre-sized crystals in confined geometries to examine the strain distributions that result. The crystal growth will employ lithographic processing techniques, made possible by the local expertise in the central clean room facilities of the London Centre for Nanotechnology. My group is world-leading in developing a method called Coherent X-ray Diffraction (CXD). Our CXD strain images of a Pb nanocrystal were published in Nature in 2006. CXD is sensitive to strain because the X-ray diffraction pattern surrounding a Bragg peak can be decomposed into symmetric and antisymmetric parts. To a good approximation, the symmetric part can be considered to come from the real part of the electron density, while the antisymmetric part is a projection of the strain field. The phasing of the data is a critical step that uses a computer algorithm, developed by us, which acts like the lens of a 3D X-ray microscope. CXD works best for nanocrystal sizes between 40nm and 5µm, for crystals strongly attached to substrates and for isolated, fiducialised arrays of crystals that can be cross-referenced with other techniques. To create nanocrystals in this size range, we will use both a bottom-up self-assembly of materials deposited onto templated substrates, designed to introduce strain, and a top-down nanosculpture approach will use lithography techniques to create strain patterns in crystalline materials associated with shapes that are carved into them. The interpretation of the images is the main intellectual output of the project. This will be compared with finite element analysis, and the deviations interpreted as unique properties attributable to the nanoscale. All project participants will work in a design, creation, analysis, interpretation, update cycle that will reveal the new basic principles of nanocrystal structure. In the long run we will transfer CXD technology to Europe: beamline I-13 at Diamond will be ready for CXD in 2011.

The investigation of the transport properties of nanoscaled objects is a strongly expanding field of nowadays solid-state physics, it attracts increasing attention either in applied science due to the potential in future applications or in basics research due to exciting quantum effects on the nanoscale. Semiconducting nanowires (NW) are single crystals with a typical diameter of 10-100nm and length of 5-10microm. Fabricating metallic leads to NWs, devices can be produced, where the electron density can be strongly varied by gates and the transport can be explored from the quasi-ballistic to the quantum dot regime. Due to their exceptional properties (e.g. band structure engineering, possibility to contact them with ferromagnetic (F), superconducting (S) leads, local gating), NW based devices open a new horizon in quantum transport. In order to be competitive in the field of experimental quantum electronics, it is essential to own sample fabrication facilities, which has not been available in the host institute. The main aim of this proposal is to set up the environment of device fabrication, which will be based on a Jeol scanning electron microscope equipped with lithography unit. The applicant will fabricate and investigate the low temperature transport properties of InAs NW based devices focusing mainly on spin injection from ferromagnetic leads and on F-S hybrid nanostructures. The fabrication facility will also support other ongoing quantum electronic projects.

The objective of the proposal is the fabrication and study of three dimensional (3D) magnetic nanowires for ultra-high density information storage. Current memory architectures are 2D, composed of one layer of active components. The extension of data storage devices into the third dimension could result in information densities of hundreds of Gb/in2, causing a technological revolution. The project aims at implementing a 3D version of the existing 2D host institution’s idea of domain wall based shift registers to store data. In this scheme, the data bits are stored using the two possible directions of the magnetisation in thin and narrow nanowires made of soft ferromagnetic materials. The fabrication of the 3D devices will be done by using a novel promising nanolithography technique: focused electron beam induced deposition (FEBID), with unique capabilities for the creation of 3D nanostructures. We have recently demonstrated the required possibility to control domain walls in cobalt nanowires created by this technique. The patterning of magnetic nanostructures by means of conventional lithography, such as electron beam lithography and ion milling, will be explored in parallel. The control of the domain walls will be probed by magneto-optical magnetometry and magneto-electrical measurements. The two directions to be investigated for the creation of 3D magnetic devices will be the stacking of 2D magnetic nanowires, and the direct fabrication of 3D nanowires. The host group possesses patents protecting the ideas presented in this proposal. The success of the project would place the European Union in a privileged position to lead the next steps in the development of Information Technology.

One-atom thin two-dimensional nanomaterials possess unique properties different from their bulk counterparts. Initiated by the discovery of graphene, many stable one atom-thick layers such as boron nitride, molybdenum disulphide, tungsten disulphide etc., have been isolated and characterized. However, the individual properties of such 2D-atomic crystals (except graphene) were modest. The combination of isolated single atomic layers into designer structures, named as 2D-heterostrcutures, is predicted to give synergetic properties. In order to harness the interesting properties the combination of various 2D-atomic crystals have to offer, a method to assemble them in a simple and scalable way is required. Currently, the only method known is manual placing of the 2D-atomic crystal layers sequentially which limits the scope of the study of such structures. The objective of the proposal is to assemble layered (each layer is one atom thick) stacks of graphene superlattices and heterostructures with other 2D-atomic crystals such as BN, MoS2, WS2 etc., by deoxyribonucleic acid (DNA)-mediated assembly. DNA mediated assembly is highly programmable by chemically specific interaction between nucleotides, length of the DNA, strength of the interactions in addition to the symmetry control of the assembled structures. Top-down lithography will be combined with bottom-up DNA assembly to fabricate seed layers of DNA for the guided assembly which lead to patterned heterostructures. This approach is targeted toward combinatorial screening of exotic properties of varied architectures of heterostructures with control over the composition of 2D-atomic crystals and spacing between the layers (controlled by DNA). The anticipated structures would be vertical atomic scale Legos of 2D-atomic crystal layers with DNA spacers.

One-atom thin two-dimensional nanomaterials possess unique properties different from their bulk counterparts. Initiated by the discovery of graphene, many stable one atom-thick layers such as boron nitride, molybdenum disulphide, tungsten disulphide etc., have been isolated and characterized. However, the individual properties of such 2D-atomic crystals (except graphene) were modest. The combination of isolated single atomic layers into designer structures, named as 2D-heterostrcutures, is predicted to give synergetic properties. In order to harness the interesting properties the combination of various 2D-atomic crystals have to offer, a method to assemble them in a simple and scalable way is required. Currently, the only method known is manual placing of the 2D-atomic crystal layers sequentially which limits the scope of the study of such structures. The objective of the proposal is to assemble layered (each layer is one atom thick) stacks of graphene superlattices and heterostructures with other 2D-atomic crystals such as BN, MoS2, WS2 etc., by deoxyribonucleic acid (DNA)-mediated assembly. DNA mediated assembly is highly programmable by chemically specific interaction between nucleotides, length of the DNA, strength of the interactions in addition to the symmetry control of the assembled structures. Top-down lithography will be combined with bottom-up DNA assembly to fabricate seed layers of DNA for the guided assembly which lead to patterned heterostructures. This approach is targeted toward combinatorial screening of exotic properties of varied architectures of heterostructures with control over the composition of 2D-atomic crystals and spacing between the layers (controlled by DNA). The anticipated structures would be vertical atomic scale Legos of 2D-atomic crystal layers with DNA spacers.

High-order harmonic generation (HHG) is an increasingly used and promising technique for achieving the extreme ultraviolet (XUV) spectral range with highest brightness, short pulse duration, and coherence. Extensive studies of this phenomenon have been mostly carried out using jets of neutral atomic gas, which have resulted in novel coherent XUV sources. However, typically observed high-order harmonics presently have the disadvantage of low conversion efficiency (10-6). This is problematic for many potential applications of HHG radiation including XUV coherent diffraction imaging, time-resolved measurements, and seeding of Free Electron Lasers. Recent studies have shown that this weakness can be partially overcome by using the ablated plasma as a nonlinear medium. An especially interesting observation, unique for harmonics originated both from gas jets, surfaces, or plasma, is the enhancement of a single harmonic, attributed to resonance with a strong radiative transition. In this way, conversion efficiencies higher than 10-5 from the pump laser radiation to the harmonics in the plateau range have been reported. The project is aimed at the enhancement of HHG efficiency from laser ablation produced on the surfaces of solid-state materials and comparison with HHG from gas jets. The milestones of the proposed investigations include (a) analysis and optimization of harmonic generation from laser plasma produced on the surface of various targets, (b) search of resonance-induced enhancement of single harmonic in the XUV range, (c) harmonic generation from the laser plumes containing nanoclusters, (d) search of the continuum in the harmonic emission near the cutoff (a characteristic signature for attosecond pulse generation), and (e) HHG from gas jets and comparison with the HHG from laser plasma. As a result of project, further improvements of the harmonic efficiency in the XUV range through the HHG from laser plasma and gas jets will be achieved.

The goal of the project is the development of a novel analytical tools allowing in-vivo speciation of metal-protein complexes. The interest in this topic is driven by the fact that this information turns out to be crucial for the understanding of the molecular mechanisms of metal transport, chelation, and biotransformation which govern the bioavailibility of the metal and resistance of an organism to metals present in high concentrations in the environment. There is sufficient evidence in human for the carcinogenicity of cadmium and cadmium compounds; therefore the project is focused on the detection and characterization of proteins that are molecular targets for cadmium in model organisms such as Arabidopsis thaliana. The analytical tools are going to be based on two complementary approaches. In the first one, consisting of in vivo screening for a non-denaturating 2D gel electrophoresis, laser ablation ICP MS detection will be developed. In the alternative approach, a library of proteins of an organism will be created by the conventional (denaturating) 2D electrophoresis and made react with cadmium. For screening the library, electrophoresis on a chip coupled with ICP MS via a dedicated nanonebulizer will be developed for the high-throughput detection of the metal-protein complexes in the biological environment. Structural information of cadmium-protein will be obtain by use of molecular mass spectrometry MALDI-TOF (matrix assisted laser desoption ionization time-of flight) MS and ES (electrospray) MS/MS.

Deficiency of natural energy resources on Earth makes advanced energy management a challenge. Efforts are taken to harness cheap, inexhaustible, eco-friendly renewable sources of energy. Among these, thermoelectric (TE) conversion is a promising principle. Best materials for TE application are non-conventional heavily doped semiconductors. In particular, high temperature stable silicides (higher manganese silicides = HMS, CrSi2 and others) represent suitable candidates for demanded TE applications operable at high temperature. A main aim of TE materials development is to improve the figure of merit ZT, which essentially depends on the energy band structure and scattering of carriers and phonons in the material. It is planned to investigate qualitatively the transport behaviour of HMS compacted from nano-sized powders, to optimize its properties by chemical synthesis, and to reach a reduction of the thermal conductivity in nano-crystalline material. Starting from the synthesis of nano-powders by melting and ball milling, forming of a nano-structure with suitable scaling will be optimized by a rapid hot pressing technology. CrSi2 and other high temperature silicides will be optimized in a similar way for high electrical and thermal conductivity. They shall be applied as contacting materials and interlayers, ending up to advanced materials and technology procedures for high temperature thermogenerators. Materials will be characterized by XRD, SEAD (structure), TEM, SEM (morphology), EDAX (analysis). Having achieved the targeted nano-structure, the TE properties will be measured in dependence on temperature for optimising the application-relevant material parameters. The performance of thermogenerator devices based on the new solutions will be tested by unique measuring techniques of the host. The fellow will deepen his knowledge and experience on TE materials and thermogenerator technology for high temperature and is expected to develop superior contacting methods.

The proposed project concerns the study of magnetoplasmonic systems, that is nanostructures exhibiting both magneto-optic (MO) properties and surface plasmon resonances (SPRs). Particularly, localized SPRs appearing in magnetic nanostructures will be studied using local probe microscopy techniques. The typical magnetoplasmonic nanostructure is a Noble-Metal/Ferromagnetic-Metal/Noble-Metal trilayer. They can be fabricated either as continuous thin films that are subsequently patterned using lithography and etching, or by lithography, evaporation and lift-off. Nanostructure arrays will be fabricated in various compositions, shapes, separations and symmetries (in particular, colloidal lithography will be used to obtain disordered arrays, whereas e-beam lithography will be used to prepare ordered ones). First, their collective optical and MO behavior will be characterized using far-field measurements. Afterwards, the local electromagnetic near-field distribution at single objects will be imaged using Scanning Near-field Optical Microscopy (SNOM). The local measurements will be correlated to the optical and MO collective measurements. Both optical-fiber SNOM and apertureles SNOM (aSNOM) measurements will be performed. Metal-coated Atomic Force Microscopy (AFM) tips will be used for aSNOM. The interest is in performing aSNOM using ferromagnetic-metal-coated AFM tips, thus allowing for Magnetic Force Microscopy (MFM) measurements to be performed simultaneously with SNOM. The illuminated light will excite surface plasmons, and the magnetic component of their electromagnetic field distribution will be imaged using MFM. Magnetoplasmonics research has been pioneered at the host group, and the proposed project is a natural continuation of the so far host activity. Magnetoplasmonics allow for the development of active plasmonic devices (their properties can be tuned with a magnetic field), with applications in photonic nanocircuits and advanced biosensors.