News & Events

Speaker: Odile Stéphan
Affiliation: LPS, Universityé Paris-Sud
Abstract Details: The field of electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) has recently achieved a succession of impressive successes linked with the development of aberration correctors, enabling atomically-resolved spectroscopy, which are now spreading worldwide. A new generation of monochromators is emerging, providing improvements in energy resolution of at least one order of magnitude and giving unprecedented access to low energy-loss ranges. Similarly, recent progress in the collection of visible-range photons emitted by a sample illuminated by a focused beam has enabled novel cathodo-luminescence (CL) experiments in STEM. In addition, new ways of exploiting fast electron beams, including combining them with beams of photons, have opened up the field of nano-optics, providing a high-spatial resolution alternative to more conventional optical techniques. Some of these new possibilities will be illustrated. Various strategies will be described for the acquisition of spatially-resolved core-level excitations signals for the mapping of functional molecular groups in graphene oxide (GO) and reduced GO [1]. Recent combined developments in EELS and CL for reaching plasmon signatures in the visible and down to the IR spectral range will be described, allowing the mapping of eigen modes in plasmonic nanostructures and a deep understanding of the physics of these excitation [2]. Finally, new possibilities for exploring the intimate link between a crystal structure (h-BN), its defects and its optical properties as revealed by nano-CL [3] will be discussed, together with some perspectives for entering the field of quantum nano-optics [4]. [1] A. Tararan, A. Zobelli, A. M. Benito, W. K. Maser, and O. Stephan, “Revisiting Graphene Oxide Chemistry via Spatially-Resolved Electron Energy Loss Spectroscopy”, unpublished [2] A. Losquin, L. F. Zagonel, V. Myroshnychenko, B. Rodríguez-González, M. Tencé, L. Scarabelli, J. Förstner, L. M. Liz-Marzán, F. Javier García de Abajo, O. Stéphan, and M. Kociak, "Unveiling Nanometer Scale Extinction and Scattering Phenomena through Combined Electron Energy Loss Spectroscopy and Cathodoluminescence Measurements", Nano Lett., 2015, 15 (2), pp 1229–1237 DOI: 10.1021/nl5043775 [3] R. Bourrellier, M. Amato, L. H. Galvão Tizei, C. Giorgetti, A. Gloter, M. I. Heggie, K. March, O. Stéphan, L. Reining, M. Kociak, and A. Zobelli, "Nanometric Resolved Luminescence in h-BN Flakes: Excitons and Stacking Order", ACS Photonics, 2014, 1 (9), pp 857–862 DOI: 10.1021/ph500141j [4] R. Bourrelier et al, unpublished
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Speaker: Hidekazu Kurebayashi
Abstract Details: The spin-orbit interaction has been providing richness and greatness of magnetism and spintronics. In solid states, it couples electron’s momentum and spins, which make it possible to electrically excite or detect spin accumulation/currents. Looking at localized spins, it is the microscopic origin of magnetic anisotropies (together with the magnetic-dipole interaction) where the sample’s real space symmetry, such as surface-induced two-fold and crystalline-induced four-fold, is reflected on the magnetic energy landscape. Along this line, we can also think of what will happen when we lower the sample symmetry to “inversion broken”. In this case, an electron propagating along one direction is, on the symmetry argument, no longer required to be on the same state as ones moving to the opposite direction. The spin-orbit interaction picks up this and causes a preferential spin direction for each electronic state, as a whole, forming spin textures in momentum space. These spin textures are a fascinating playground for developing spin-conversion effects. Although the electric excitation of spin textured materials has been known as the Edelstein effect [1] for more than two decades, its real spintronic use, e.g. magnetisation control [2], has been much more recent interest. In this talk, I will summarise our recent results on spin-conversion effects using GaMnAs spin textures. I will show microscopic origins of current-induced magnetisation control by the Edelstein effects in single ferromagnetic layers [3], as well as by non-magnetic layers [4]. In addition, I will touch upon charge pumping experiments by magnons [5]. [1] Edelstein, Solid State. Comm. 73 233 (1990). [2] Chernyshov, et al., Nature Phys., 5 656 (2009). [3] Kurebayashi, et al., Nature Nanotech, 9 211 (2014). [4] Skinner et al., Nature Comm. 6 6730 (2015). [5] Ciccarelli et al., Nature Nanotech. 10 50 (2015).
About the Speaker: I have broad interests in spin transport, generation, manipulation and beyond, with a determination to contribute to furthering our scientific understanding and technological abilities. I am at the moment very much fascinated by a diverse range of phenomena arising from the spin-orbit interaction, in particular, that projects the real space (sample) structures and symmetries into spin structures in the (electronic) momentum space. These form a pivotal role in our modern physics and materials science research, often in the nanoscale, that I feel there are much more to explore. Understanding of the spin-orbit natures in condensed matter and resultant rational selections of appropriate materials&structures can potentially push the boundary of what it calls the state-of-the-art in the nanotechnology.
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Speaker: László Forró
Affiliation: EPFL, Switzerland
Abstract Details: A major contribution of nanotechnology to our life is the controlled synthesis of a large variety of nanomaterials. Due to their unique physico-chemical properties these nanostructures are considered to be of great benefit for many applications within engineering, electronics, alternative energy production or nanomedicine. Although the expectations are large concerning the improvement of our everyday life due to the engineered nanomaterials, there is a forecasted expansion of their manufacturing, which makes likely that intentional and unintentional human and environmental exposure will increase in the near future. As a result there is a growing worry related to their possible health hazards, as some of them strongly resemble to asbestos. Motivated by this issue, we have investigated the acute cellular toxicity associated with five model nanomaterials, namely carbon nanotubes, boron nitride nanotubes, titanium dioxide nanofilaments, photovoltaic perovskite nanowires and graphene oxide in vitro using a multitude of techniques. Our findings highlight an important role of distinct physico-chemical properties such as the shape in case of carbon based nanomaterials, the surface modification and geometry (length, width) relevant to the toxicity of titanium dioxide nanofilaments and the tortuosity in determining the toxic potential of boron nitride nanotubes. In addition to the identified nanomaterial characteristics, we pinpoint that the target cell type is also a critical determinant of the cellular response, which is variable between different cell types and is likely linked to their physiological function. Acknowledgment: The work is performed in collaboration with Ines Benmessaoud, Anne- Laure Mahul, Hilal Lashuel, Massimo Spina, Bohumil Maco, Endre Horvath, Lenke Horvath, Arnaud Magrez and Beat Schwaller.
About the Speaker: Lazslo Forro is a Full Professor at the Institute of Physics of the Ecole Polytechnique Federale de Lausane (EPFL), in Switzerland, and director of the EPFL Laboratory for the Physics of Complex Materials (LPCM). The activity of the LPCM covers a broad range of topics, from superconductivity to the movement of dislocations, to living cells, all with complexity as the common denominator. The lab provides a single crystal growth facility with nano-sized to macroscopic samples, synthesizing more than 100 different compounds. Through studying the basic physical properties of novel electronic materials like cuprate or pnictide superconductors, organic kagome lattices, low-dimensional conductors, graphene, magnetic semiconductors or anatase single crystals, one of the goals of LPCM beyond the exciting physics they reveal, is to learn how one can improve the materials quality. The group is also strongly involved in establishing bridges between the physical and biological sciences, the hard and soft matter themes. One result of this effort is the bi-annual organization of the international conference “From Solid State to Biophysics”.
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Speaker: Bent Weber
Affiliation: Monash University, Australia
Abstract Details: One of the most intriguing directions in Nanotechnology is the manipulation of individual atoms in the solid state to create functional atomic-scale electronic devices. I will show that such devices can be fabricated using scanning tunnelling microscopy (STM), and that their electronic properties can be made accessible by STM and electron transport measurements down to sub-Kelvin temperatures. To this end I will introduce a range of atomic-scale silicon devices, fabricated by a unique combination of STM hydrogen lithography, phosphorus delta-doping and molecular beam epitaxy. Building up from basic components such as atomic-scale wiring and few-atom quantum dots, I will show how these structures can be integrated to construct complex circuits allowing the time-resolved electrical detection individual electron spins for silicon quantum information processing. I will provide a brief outlook on progress towards the atomic-scale nanostructuring of next- generation electronic materials such as graphene and the layered transition metal dichalcogenides (TMDCs).
About the Speaker: Bent received his Ph.D. from the University of New South Wales (UNSW) in Sydney, Australia. As part of the Centre for Quantum Computation and Communication Technology (CQC2T), he has made contributed to the development of an atomic-precision fabrication scheme for the engineering of atomic-scale electronic devices for spin-based quantum information processing. In his current role at the Centre for Atomically Thin Materials (MCATM), Monash University, Bent is applying his expertise in atomic-scale nanostructuring to the next generation electronic materials graphene and the layered transition metal dichalcogenides (TMDCs). In this role he has recently been awarded with the Discovery Early Career Researcher Award (DECRA) fellowship by the Australian Research Council (ARC).
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Speaker: Justin Song
Affiliation: A*STAR & NTU, Singapore
Abstract Details: Plasmons, the collective oscillations of interacting electrons, possess emergent properties that dramatically alter the optical response properties of metals. We predict the existence of a new class of plasmons – chiral Berry plasmons (CBPs) – for a wide range of metallic systems including anomalous Hall metals and gapped Dirac materials. As we show, in these materials the interplay between Berry curvature and electron-electron interactions yields chiral plasmonic modes at zero magnetic field. The CBP modes are confined to system boundaries, even in the absence of topological edge states, with chirality manifested in split energy dispersions for oppositely directed plasmon waves. We unveil a rich CBP phenomenology and propose setups for realizing them, including in anomalous Hall metals and optically-pumped 2D Dirac materials. Realization of CBPs will offer a new paradigm for magnetic field-free, sub-wavelength optical non-reciprocity, in the mid IR-THz range, with tunable splittings as large as tens of THz, as well as sensitive all-optical diagnostics of topological bands."
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Speaker: SCIC
Abstract Details:

SPRING Singapore administers the National Standardisation Programme under the direction of the industry-led Standards Council of Singapore. As of April 2011, SPRING Singapore has appointed the Singapore Chemical Industry Council Limited (SCIC) to manage the Chemical Standards Committee (CSC) and its Technical Committees.

The Standards Development Organisation at SCIC (SDO @ SCIC) is organising a nanotechnology standards adoption workshop in Mar 2016. The intention of this workshop is to provide detailed information on the development of nanotechnology standards related to measurement and characterisation with key inputs from manufacturers etc. for equipment used for nanocharacterisation techniques. The applications of nanocharacterisation techniques and challenges in standardisation will also be shared at the workshop.

Brief Programme:

· Introduction to Singapore’s role in international nanotechnologies standardization
· Overview of ISO/TC 229/JWG 2 standards and its importance
· Nanocharacterisation techniques and challenges in standardisation
· Nanomeasurement techniques
· Protocols and standards for graphene flake characterization

Registration fee: FREE
Closing date for registration: 20 Mar 2016
Seats are limited and would be on first-come-first serve basis.
Should you require further details, please do not hesitate to contact Ms Jillian Chin at 6267 9661 or email her at jillian@scic.sg.

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Speaker: Rostislav Aleksandrov Doganov
Affiliation: CA2DM, NUS
Abstract Details: This month marks two years since the first publications on exfoliated ultrathin black phosphorus. During this time the research on this novel 2D semiconductor has rapidly increased and now amounts to more than 500 papers. Our lab at CA2DM has been actively involved in the study of the electronic transport properties of few-layer phosphorene from the very start, and in this talk I will share my perspective on the topic. I will cover already published experimental results from the past two years, as well as recent results on the controllable electron doping of few-layer black phosphorus using metal adatoms.
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Speaker: László Forró
Affiliation: EPFL, Switzerland
Abstract Details: Recently, it has been shown by the Snaith [1] and Graetzel [2] groups that CH3NH3PbI3 is very promising material in photovoltaic devices reaching light conversion efficiency (?) up to 21%. A strong research activity has been focused on the chemistry of the material to establish the most important parameters which could further improve ? and to collect photons from a broad energy window. The major trend in this field is in photovoltaic device engineering although the fundamental aspects of the material are not yet understood. In my lab we have devoted considerable effort to the growth of high quality single crystals at different length scales, ranging from large bulk crystals (up to 100 mm3) through nanowires [3,4] down to quantum dots of tens of nanometers of linear dimensions. The structural tunability of the material allows to study a broad range of physical phenomena including electrical and thermal transport, magnetism and optical properties which will be reported in this presentation together with some device applications [5]. Acknowledgement: The work has been performed in collaboration with Endre Horvath, Massimo Spina, Balint Nafradi, Alla Araktcheva, Andrea Pisoni, Jacim Jacimovic and the Van der Marel group. This work was partially supported by the ERC Advanced Grant (PICOPROP#670918). 1. Lee, M. M. et al.,Science 338, 643-647 (2012). 2. Stranks, S. D. et al.. Science, 342, 341?344, (2013). 3. Horvath et al., Nano Letters 14, 6761, (2015) 4.Spina et al., (2016) Scientific Reports, 6, 1 5.Spina et al., (2015) Small, 11, 4823
About the Speaker: Lazslo Forro is a Full Professor at the Institute of Physics of the Ecole Polytechnique Federale de Lausane (EPFL), in Switzerland, and director of the EPFL Laboratory for the Physics of Complex Materials (LPCM). The activity of the LPCM covers a broad range of topics, from superconductivity to the movement of dislocations, to living cells, all with complexity as the common denominator. The lab provides a single crystal growth facility with nano-sized to macroscopic samples, synthesizing more than 100 different compounds. Through studying the basic physical properties of novel electronic materials like cuprate or pnictide superconductors, organic kagome lattices, low-dimensional conductors, graphene, magnetic semiconductors or anatase single crystals, one of the goals of LPCM beyond the exciting physics they reveal, is to learn how one can improve the materials quality. The group is also strongly involved in establishing bridges between the physical and biological sciences, the hard and soft matter themes. One result of this effort is the bi-annual organization of the international conference “From Solid State to Biophysics”.
Click HERE for directions

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Speaker: Edwin Barnes
Affiliation: Virginia Tech University, USA
Abstract Details: Dirac materials have been at the forefront of condensed matter research over the past decade following breakthroughs in graphene transport experiments. The relativistic-like linear dispersion of quasiparticles near the Dirac point leads to a variety of intriguing phenomena, among which are many-body interaction effects that both resemble and strongly contrast with quantum electrodynamics. Most notably, graphene experiments have revealed a strong Dirac cone squeezing effect due to electron-electron interactions. This and related phenomena can arise not only in graphene, but also in three-dimensional Dirac-Weyl semimetals, albeit with many qualitative differences due to the renormalization of both charge and Fermi velocity in three dimensions. I will describe our efforts to develop a quantitative and predictive theory of many-body phenomena in both graphene and 3D Dirac-Weyl semimetals.
About the Speaker: Professor Barnes' research interests span a number of topics in quantum condensed matter theory, including spin-based quantum computation, dynamical error suppression in quantum systems, driven non-equilibrium spin dynamics, non-equilibrium physics in 2D materials, many-body interactions in graphene, and novel topological materials such as topological insulators and Weyl semimetals. There is a particular emphasis on bridging formal, mathematical constructs with research that is closely connected to experiment.
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Speaker: Lu Junpeng
Abstract Details: Optical pump-terahertz (THz) probe spectroscopy (OPTP) is a specific technique to investigate the carrier dynamics in nanostructures. In comparison to time-resolved PL technique, OPTP would not be influenced by low PL efficiency of the materials. As compared to other common ultrafast spectroscopy techniques, the powerful nature of OPTP spectroscopy stems from the facts that it is a coherent technique that can make both amplitude and phase measurements. This could reveal a wealth of information about materials that interact with THz wave, where the typical charge carrier scattering time is in picosecond range which corresponds to THz frequency range in the electromagnetic spectrum. This enables THz radiation interacts in a specific manner with charge carriers, facilitating THz wave the ideal probe for carrier dynamics. Furthermore, OPTP is also an effective tool to elucidate the defect-related trapping process due to the high sensitivity of THz probe to the carrier density and mobility.
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