Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session C32: DMP Prize SessionInvited Prize/Award
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Sponsoring Units: DMP Chair: Amanda Petford-Long, Argonne National Laboratory Room: LACC 408A |
Monday, March 5, 2018 2:30PM - 3:06PM |
C32.00001: James C. McGroddy Prize for New Materials Talk: Fundamental discoveries about graphene and their implications to date Invited Speaker: Rodney S. Ruoff A variety of our scientific discoveries about graphene (and related materials such as ‘graphene oxide’) will be presented, and advances towards practical applications (that have been made typically by others, but sometimes by us) based on such scientific breakthroughs will be described. For several cases this ‘trajectory’ from science of ‘flake graphene’ and ‘CVD graphene’ (graphene grown on copper foil) towards technology and even to commercialization has happened relatively quickly. Several examples of current fundamental research on new materials in our \textit{Center for Multidimensional Carbon Materials} (an Institute for Basic Science Center) at UNIST will be given. |
Monday, March 5, 2018 3:06PM - 3:42PM |
C32.00002: Dissimilar Materials Epitaxy: Metallic Compound/III-V Semiconductor Heterostructures Invited Speaker: Christopher Palmstrom The ability to integrate dissimilar materials with different crystal structures and properties enables heterostructures to be developed with new functionality. Lattice matching, interfacial bonding and reactions are issues that need to be addressed for heteroepitaxial growth of dissimilar materials. Molecular beam epitaxial (MBE) growth, in combination with in-situ and ex-situ atomic level characterization techniques, enables studies of nucleation and epitaxial growth processes and interfacial reactions. We have investigated the growth of a number of dissimilar epitaxial materials on III-V semiconductors and metal oxides including elemental ferromagnets and superconductors, ferromagnetic and half metal Full-Heusler compounds (Co$_{2}$ MnSi, Co$_{2}$ FeSi,..), semiconducting (CoTiSb, NiTiSn,..) and topological Half-Heusler compounds (PtLuSb), and rare earth monopnictide-III- V semiconductor nanocomposites. These studies have aimed at tailoring of interfacial and material properties of these dissimilar materials heterostructures for targeting novel applications including spintronics and topological quantum computing. |
Monday, March 5, 2018 3:42PM - 4:18PM |
C32.00003: Edward A. Bouchet Award Talk: Nanoparticles with Five-fold Symmetry Invited Speaker: Miguel Yacaman In materials science structure of bulk crystals play a paramount role. Bulk crystals abide by the rules of symmetry, order and periodicity which are fundamental characteristics of bulk crystals. It is well known that the only rotational symmetries that are allowed correspond to angular rotations of 2$\pi $, \textpm $\pi $, \textpm 2$\pi $/3 and \textpm $\pi $/2, which correspond to rotational symmetries of 1-fold, 2-fold, 3-fold and 4-fold. However, n$=$5, n$=$10 and n$=$7; are not allowed. There are no natural crystals with five-fold or ten-fold symmetry. Researchers have synthetize quasicrystals that indeed have five-fold symmetry. Two important differences make quasicrystals and crystals different. Quasicrystals a) have order but no translational symmetry and b) they are always formed by at least two different kinds of atoms. No quasicrystal form by only one single element has been found. In the case of small crystallites (or non-particles) it seems to be a different situation since decahedral and icosahedral particles are frequently and stubbornly observed. One important question is: Are the decahedral and icosahedral particles really five-fold or tenfold symmetry? Experimental evidence indicates that the five-fold symmetry comes from 5 or 20 twins arranged to form a decahedron or icosahedron polyhedral shape. Every twin crystal produces a diffraction pattern. When all the patterns are put together, a five-fold pattern is obtained. This is nevertheless a curios fact, and shows a remarkable preference for five-fold shapes. In this talk, we discuss the factors that result in a certain preference for five--fold shapes in nanoparticles and mechanisms that stabilize them. |
Monday, March 5, 2018 4:18PM - 4:54PM |
C32.00004: Symmetry Matters: Machine-learning of Scalar and Tensorial Atomic-Scale Properties Invited Speaker: Michele Ceriotti Determining the stability of molecules and condensed phases is the cornerstone of atomistic modelling, underpinning our understanding of chemical and materials properties and transformations. Bayesian statistical learning, combined with local descriptors of chemical environments, provides a unified framework to predict atomic-scale properties [1]. The framework is very general, and can be applied equally well to solids, surfaces, molecules and biological systems. It can predict molecular energetics with chemical accuracy and distinguishes active and inactive protein ligands with more than 99% reliability. The universality and the systematic nature of this framework provides new insight into the potential energy surface of materials and molecules. The method can also be extended to yield a "symmetry-adapted" Gaussian process regression [2] approach that is capable of learning efficiently tensorial properties by enforcing automatically the appropriate transformation rules. [1] A. P. Bartok, S. De, C. Poelking, N. Bernstein, J. Kermode, G. Csanyi, and M. Ceriotti, Sci. Adv. 3, e1701816 (2017). [2] A. Grisafi, D. M. Wilkins, G. Csányi, and M. Ceriotti, arXiv:1709.06757 (2018). |
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