Fall 2017

September 8, 2017 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: Fan Zhang, University of Texas
Host: E. Rossi
Title: Symmetry Protected Topological Matter
Abstract: In history, solid states are characterized by the symmetries they respect and also by those they break. Not only does this idea distinguish graphite and diamond, but also ferromagnets and superconductors. Recently, the discovery of topological insulators has revealed a new paradigm that solid states respecting the same symmetries can be topologically distinct. The same idea relates a cup and a donut, yet distinguishes a sphere and a torus. Such a topological viewpoint has created a revolution in condensed matter science that has far ranging implications over coming decades. In this talk, I will introduce how the topological insulators arise from band inversion, and how they are protected by symmetries and enriched under symmetry breaking. I will then generalize these essential ideas to other experimentally feasible systems such as superconductors with Weyl and Majorana excitations. Fascinating and significant implications including experimental signatures and potential applications will be discussed.

September 15, 2017 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: Deyu Lu, Center for Functional Nanomaterials, Brookhaven National Laboratory
Host: S. Zhang
Title: First principles modeling of electronic excitations: From basic understanding to materials
applications
Abstract: Electronic excitations are fundamental physical processes. Spectroscopic information, including absorption and emission spectra, from electron or photon probes is crucial for materials characterization and interrogation. When experimental data are supplemented and interpreted by first principles atomic modeling, a coherent physical picture can be established to provide physical insights into the intriguing structure-property-function relationship of functional materials. In this talk, the significance of the first principles modeling of electronic excitations is highlighted with three examples. In the first example, we investigated the oxygen 1s corelevel binding energy shift of bilayer silica films on Ru(0001) under different surface oxygen coverages in the X-ray photoelectron spectroscopy (XPS) measurement. Our study revealed that the binding energy shift is an electrostatic effect caused by the interplay of the surface and interface dipole moments. In the second example, we applied ab intio X-ray absorption near edge structure (XANES) modeling for spinel lithium titanate (Li4/3Ti5/3O4), an appealing lithium ion battery material. We identified key spectral features as fingerprints for quantitative assessment of the structural transformation during lithiation. In the third example, we are motivated to develop a local representation of the microscopic dielectric response function of valence electrons, which is a central physical quantity that captures the many-electron correlation effects. Although the response function is non-local by definition, a local representation in real space can provide insightful understanding of its chemical nature and improve the computational efficiency of first principles excited state methods. We applied the local dielectric theory to calculate the molecular polarizability of water and investigated the effects of the local field and hydrogen bonds. This research used resources of the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, at Brookhaven National Laboratory under Contract No. DESC0012704.

September 22, 2017 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: 
Marc Sher, William & Mary Physics
Title:
The Higgs Boson, five years later
Abstract: 
The discovery of the Higgs boson in 2012, almost fifty years after it had been predicted, was an extraordinary achievement.    It explained the origin of mass for all elementary particles.   In this talk, I will discuss the Standard Model and explain the importance of the Higgs and describe its properties.   The experimental results since the discovery will be reviewed.    I will then discuss the next steps in exploring the properties of the Higgs, future prospects and physics “beyond the Standard Model”.   This talk should be accessible to undergraduate juniors

October 6, 2017 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: 
Natalia Noginova, NSU
Host: Irina Novikova
Title: 
Plasmon Drag and Optical Magnetism in Plasmonic Structures and Metasurfaces
Abstract: 
Plasmonic systems and metamaterials attract much attention due to their unusual properties and new opportunities for various applications. Such systems are also extremely interesting from fundamental point of view as they demonstrate novel or strongly modified effects associated with light matter interactions.  In this talk I will discuss two directions of my research: Coupling of photons,  plasmons and electrons in nanostructured metal, and Probing of optical magnetism in plasmonic systems and metasurfaces.

October 27, 2017 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: 
Kent Yagi, UVA
Host: 
Marc Sher
Title:
Probing Extreme Gravity with Gravitational Waves
Abstract: 
The binary black hole merger events recently discovered by the LIGO and Virgo Collaboration offer us excellent testbeds for exploring extreme (strong and dynamical-field) gravity that was previously inaccessible. In this talk, I will first review the current status of the gravitational wave events confirmed so far and what surprises these historical discoveries brought us. I will next describe how one can use such new events to probe the extreme nature of gravity and fundamental aspects of General Relativity. I will then explain what comes next in terms of testing gravity with gravitational waves, in particular using neutron star binary mergers as new sources. I will describe how one can use approximate universal relations ("I-Love-Q relations") among certain neutron star observables that are almost insensitive to the unknown stellar internal structure to probe extreme gravity. I will conclude with a summary of important future directions.

November 3, 2017 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: 
Wes Gohn, Kentucky
Host: 
Wouter Deconinck
Title: 
(g-2)_mu
Abstract:

November 10, 2017 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker:
 Michael Katsnelson, Radbound University
Host: 
E. Rossi
Title: 
Abstract:

December 1, 2017 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker:
Joshua Magee
Host: 
D. Armstrong
Title: 
Abstract: