A5053669564- Quantum and electron transport phenomena
- Molecular Junctions and Nanostructures
- Graphene research and applications
- Advancements in Semiconductor Devices and Circuit Design
- Semiconductor materials and devices
- Veterinary Medicine and Surgery
- Growth Hormone and Insulin-like Growth Factors
- Nanowire Synthesis and Applications
- Advanced Memory and Neural Computing
- Stress Responses and Cortisol
- Advanced Thermodynamics and Statistical Mechanics
- Adrenal Hormones and Disorders
- Thyroid Disorders and Treatments
- Cancer, Hypoxia, and Metabolism
- Semiconductor Quantum Structures and Devices
- Advanced Thermoelectric Materials and Devices
- Quantum-Dot Cellular Automata
- Electron and X-Ray Spectroscopy Techniques
- Nanopore and Nanochannel Transport Studies
- Surface and Thin Film Phenomena
- Advanced biosensing and bioanalysis techniques
- Pituitary Gland Disorders and Treatments
- Electrochemical Analysis and Applications
- Thermal properties of materials
- Neuroendocrine regulation and behavior
Queen Mary University of London
2019-2024
University of Oxford
2014-2023
Utrecht University
2002-2020
Oxfam
2015-2019
Science Oxford
2019
UNSW Sydney
2011-2016
Centre for Quantum Computation and Communication Technology
2011-2016
Delft University of Technology
2008-2013
Institut polytechnique de Grenoble
2010
The University of Melbourne
2010
Abstract Only single-electron transistors with a certain level of cleanliness, where all states can be properly accessed, used for quantum experiments. To reveal their exceptional properties, carbon nanomaterials need to stripped down single element: graphene has been exfoliated into sheet, and nanotubes vibrational, spin coherence properties only after being suspended across trenches 1–3 . Molecular nanoribbons 4–6 now provide nanostructures single-atom precision but suffer from poor...
Quantum effects in nanoscale electronic devices promise to lead new types of functionality not achievable using classical components. However, quantum behaviour also presents an unresolved challenge facing electronics at the few-nanometre scale: resistive channels start leaking owing tunnelling. This affects performance transistors, with direct source-drain tunnelling degrading switching ratios and subthreshold swings, ultimately limiting operating frequency due increased static power...
We demonstrate a robust graphene-molecule-graphene transistor architecture.
We report transport measurements on a graphene-fullerene single-molecule transistor. The device architecture where functionalized C60 binds to graphene nanoelectrodes results in strong electron-vibron coupling and weak vibron relaxation. Using combined approach of spectroscopy, Raman DFT calculations, we demonstrate center-of-mass oscillations, redox-dependent Franck-Condon blockade, regime characterized by avalanche tunnelling
Significance Continuation of Moore’s law to the sub–10-nm scale requires development new technologies for creating electrode nanogaps, in architectures which allow a third electrostatic gate. Electroburnt graphene junctions (EGNs) have potential fulfill this need, provided their properties at moment gap formation can be understood and controlled. In contrast with mechanically controlled break junctions, whose conductance decreases monotonically as junction approaches rupture, we show that...
Abstract In quantum simulation, many-body phenomena are probed in controllable systems. Recently, simulation of Bose–Hubbard Hamiltonians using cold atoms revealed previously hidden local correlations. However, fermionic Hubbard such as unconventional superconductivity and spin liquids more difficult to simulate atoms. To date the required single-site measurements cooling remain problematic, while only ensemble have been achieved. Here we a two-site Hamiltonian at low effective temperatures...
Charge transport through molecular junctions is often described either as a purely coherent or classical phenomenon, and using the Landauer-Büttiker formalism Marcus theory (MT), respectively. Using generalised quantum master equation, we here derive an expression for current junction modelled single electronic level coupled with collection of thermalised vibrational modes. We demonstrate that aforementioned theoretical approaches can be viewed two limiting cases this more general present...
Since the early days of quantum mechanics, it has been known that electrons behave simultaneously as particles and waves, now electronic devices can harness this duality. When are shrunk to molecular scale, is unclear under what conditions does electron transmission remain phase-coherent, molecules usually treated either scattering or redox centers, without considering wave–particle duality charge carrier. Here, we demonstrate remains phase-coherent in porphyrin nanoribbons connected...
Single layer graphene nano-gaps are fabricated by applying the method of feedback-controlled electroburning to notched ribbon devices, which plasma etched from CVD grown that is wet-transferred onto pre-patterned metal electrodes. Electrical and structural characterizations show nanometer size gaps form at center notch. We have processed a total number 1079 devices using this with fabrication yield 71%. Our results demonstrate precise control over position nano-gaps, open up possibility...
We report quantum interference effects in the electrical conductance of chemical vapor deposited graphene nanoconstrictions fabricated using feedback controlled electroburning. The observed multimode Fabry-Pérot interferences can be attributed to reflections at potential steps inside channel. Sharp antiresonance features with a Fano line shape are observed. Theoretical modeling reveals that these resonances due localized states constriction, which couple delocalized also give rise patterns....
Abstract The effectiveness of five different anchor groups for non‐covalent interfacing to graphene electrodes are compared. A family six molecules is tested in single‐molecule junctions: consist the same porphyrin core with groups, and sixth a reference molecule without groups. junction formation probability (JFP) has strong dependence on group. Larger anchors give higher binding energies surface, correlating JFPs. best 1,3,8‐tridodecyloxypyrene 2,5,8,11,14‐pentadodecylhexa‐ peri...
Although it was demonstrated that discrete molecular levels determine the sign and magnitude of thermoelectric effect in single-molecule junctions, full electrostatic control these has not been achieved to date. Here, we show graphene nanogaps combined with gold microheaters serve as a testbed for studying thermoelectricity. Reduced screening gate electric field compared conventional metal electrodes allows position dominant transport orbital by hundreds meV. We find power factor...
The influence of nanostructuring and quantum confinement on the thermoelectric properties materials has been extensively studied. While this made possible multiple breakthroughs in achievable figure merit, classical confinement, its effect local Seebeck coefficient mostly neglected, as Peltier general due to complexity measuring small temperature gradients locally. Here we report that reducing width a graphene channel 100 nm changes by orders magnitude. Using scanning thermal microscope...
Graphene provides a two-dimensional platform for contacting individual molecules, which enables transport spectroscopy of molecular orbital, spin, and vibrational states. Here we report single-electron tunneling through molecule that has been anchored to two graphene leads. Quantum interference within the leads gives rise an energy-dependent transmission fluctuations in sequential tunnel-rates. The lead states are electrostatically tuned by global back-gate, resulting distinct pattern...
High fidelity entanglement of an on-chip array spin qubits poses many challenges. Spin-orbit coupling (SOC) can ease some these challenges by enabling long-ranged via electric dipole-dipole interactions, microwave photons, or phonons. However, SOC exposes conventional to decoherence from electrical noise. Here, we propose acceptor-based spin-orbit qubit in silicon offering long-range at a sweet spot where the is protected The relies on quadrupolar with interface and gate potentials. As...
We demonstrate a single-hole transistor using an individual acceptor dopant embedded in silicon channel. Magneto-transport spectroscopy reveals that the ground state splits as function of magnetic field into four states, which is unique for single hole bound to bulk semiconductor. The two lowest spin states are heavy (|mj| = 3/2) and light 1/2) hole-like, two-level system can be electrically driven characterized by dependent long relaxation time, properties interest qubits. Although bulklike...
Graphene nanogap electrodes have been of recent interest in a variety fields, ranging from molecular electronics to phase change memories. Several reports highlighted that scaling graphene nanogaps even smaller sizes is promising route more efficient and robust memory devices. Despite the significant interest, operating limits these are completely unknown. In this paper, we report on our observations consistent voltage driven resistance switching sub-5 nm nanogaps. We find such electrical an...
When designing a molecular electronic device for specific function, it is necessary to control whether the charge-transport mechanism phase-coherent transmission or particle-like hopping. Here we report systematic study of charge transport through single zinc-porphyrin molecules embedded in graphene nanogaps form transistors, and show that depends on chemistry molecule-electrode interfaces. We van der Waals interactions between anchoring groups yield characteristic Coulomb blockade with...
Differentiation between hypothyroidism and nonthyroidal illness in dogs poses specific problems, because plasma total thyroxine (TT4) concentrations are often low illness, thyroid stimulating hormone (TSH) frequently not high primary hypothyroidism.The serum of the common basal biochemical variables (TT4, freeT4 [fT4], TSH) overlap with but, stimulation tests quantitative measurement thyroidal 99mTcO4(-) uptake, differentiation will be possible.In 30 TT4 concentration, final diagnosis was...
The putative stimulation of adrenal steroid production by immunoglobulins (Igs) five patients with pigmented adrenocortical micronodular dysplasia and clinical Cushing's syndrome was investigated. Ascorbate depletion, a process linked to production, measured cytochemical bioassay employing guinea pig explants in organ culture exposed IgG from the normal subjects. We also cortisol these segments during 5-h period using RIA. For positive reference values we studied effects ACTH-(1-39),...
Background Information on the genetic events leading to thyroid cancer in dogs is lacking. Hypothesis/Objectives Upregulation of PI3K/Akt pathway has an important role tumorigenesis carcinoma dogs. Animals Fifty‐nine with and 10 healthy controls. Methods Quantitative RT ‐ PCR was performed for VEGFR‐1 , VEGFR‐2 EGFR PIK3CA PIK3CB PDPK1 PTEN AKT1 AKT2 COX‐2 CALCA . Mutation analysis known hotspots RAS (N K H) BRAF RET entire coding region Results Forty‐three (73%) had follicular cell ( FTC )...