Fall 2019

September 13, 2019 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: Georg Schwiete, University of Alabama
Host: E. Rossi
Title: Transport phenomena in two-dimensional electron systems
Abstract: In this talk, I will discuss a number of physical mechanisms that have a strong influence on electronic transport in two-dimensional systems. At the lowest temperatures, localizating and delocalizing tendencies compete near a metal-insulator transition. At intermediate temperatures, the transport is dominated by scattering of electrons on a self-consistently created potential near impurities. When further increasing the temperature, electron-electron collisions gain importance and eventually lead to hydrodynamic behavior in the electronic system. I will explain how these mechanisms and phenomena reveal themselves in different ways in electric, thermal and thermoelectric transport.

September 20, 2019 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: Amlan Biswas, University of Florida
Host: M. Qazilbash
Title: Magnetoelectrism” in crystals: Controlling magnetic anisotropy with strain and electric fields
While the effect of an electric field on magnetism is firmly established, we are much more familiar with the equation M = cmH than with M=αE, where cm is the magnetic susceptibility and α quantifies the “magnetoelectric effect.” A reason for this unfamiliarity is that α is negligible for most magnetic materials. I will discuss our experimental results on controlling the direction (and not the magnitude) of M in the compound LaPrCaMnO3 with strain and electric fields. I will describe how the two main sources of magnetic anisotropy, viz. magnetocrystalline and shape anisotropy, can be modified using strain and electric fields due to the first order nature of the magnetic transition in LaPrCaMnO3. Ongoing experiments in our research group have been designed to fabricate and study these materials and further enhance their magnetoelectric properties.

October 4, 2019 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: Sami Mitra, Editor of Physical Review Letters
Host: E. Rossi
Title: PRL at 60: You have your physics results, now what?
In a talk that I am hoping will morph into a free-flowing Q and A session, I will discuss the role that PRL plays in disseminating your physics results. The process is a cascading sequence that entails interacting with journal editors, referees, conference chairs, journalists, department chairs, deans, funding agencies, and others. The tools, however, have changed in recent years; the arrival of social media, search engines, and electronic repositories have us in a state of flux. PRL published its first paper 60 (plus 1) years ago. Let's look back and forward.

About the Speaker: 
Samindranath (Sami) grew up in Kolkata and Delhi, and received his Ph.D. at Indiana University (Bloomington) in 1994 on theoretical aspects of the quantum Hall effect. After working on chemical physics at the Albert Einstein College of Medicine in New York City, he joined Physical Review Letters. Among his other responsibilities are papers on transport properties in semiconductors, 2D materials, and mesoscopic systems.

October 25, 2019 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: Patrick Meade, SUNY Stony Brook
Host: C. Carone
Future colliders and the Higgs
Abstract:  I will discuss the current status of LHC measurements and potential discovery prospects at future e+e- and pp colliders focusing on the Higgs.  I will emphasize how many of the unanswered questions about the Standard Model of particle physics are connected to measuring properties of the Higgs with higher precision. In particular I will point out how improving quantitative precision in certain measurements can lead to qualitative changes about our understanding of the universe.  I will primarily focus on a few examples from flavor physics and cosmology in making this case.

November 1, 2019 (Friday) 4:00-5:00p.m. Small Hall 111
Speaker: Jorge Piekarewicz, Florida State University
Host: J. Dudek
Nuclear Astrophysics in the New Era of Multimessenger Astronomy
Abstract: One of the overarching questions animating nuclear physics today is "How does subatomic matter organize itself". Neutron stars are cosmic laboratories uniquely poised to answer this fundamental question. The historical first detection of a binary neutron star merger by the LIGO-Virgo collaboration is providing fundamental new insights into the astrophysical site for the r- process and on the nature of neutron-rich matter. In turn, the study of nuclei at new exotic-beam facilities throughout the world will help elucidate the underlying dynamics of the r-process and the structure, dynamics, and composition of neutron stars. In this presentation I will discuss how this synergy — in combination with nuclear physics insights, modern theoretical approaches, and powerful statistical ideas — can pave the way to understanding these fascinating objects.

November 8, 2019 (Friday) 4:00-5:00p.m. Small Hall 111
Tom Gallagher, University of Virginia
B. Cooke
Exploring Strong fields with Rydberg Atoms and Microwaves
Multiphoton ionization of atoms by intense laser pulses has led to surprising results, notably above threshold ionization and the production of high lying states accompanying ionization. Using Rydberg atoms and microwaves, the same phenomena can be observed and studied in detail. Although the production of high lying Rydberg states was not observed in early microwave ionization experiments, in better controlled recent experiments it has been. How the high lying states are produced is clarified by spectroscopy in the presence of a microwave field, which reveals a long periodic structure consisting of peaks removed from the ionization limit by integral multiples of the microwave frequency. The Floquet states represented by these peaks exhibit the same ponderomotive AC Stark shift as the limit, and production of high lying states occurs when they are shifted into resonance with an initial Rydberg state. The series of Floquet states extends well above the ionization limit, i. e., laser excitation above the limit in the presence of the microwave field leads to bound states. These observations can be described by a simple model, which is verified by time domain measurements.

November 14, 2019 (Friday) 4:00-5:00p.m. Small Hall 111
Dr. Z. Aziza Baccouche,  Aziza Productions Inc.
C. Carone
Having Vision
Abstract: Dr. Baccouche will be talking about her life experiences

November 22, 2019 (Friday) 4:00-5:00p.m. Small Hall 111
Amy Nicholson, University of North Carolina - Chapel Hill
C. Monahan
Exploring beyond the Standard Model with Lattice QCD
While the Standard Model (SM) of particle physics has been enormously successful in describing the world around us, there still remain many important and unanswered questions requiring Beyond the SM (BSM) physics. One way to experimentally test the fundamental symmetries of the SM in searches for potential violations is to utilize properties of atomic nuclei which enhance these rare events. Connecting experimental signals from nuclear environments to a particular BSM model requires the numerical solution of Quantum Chromodynamics (QCD), a cornerstone of the SM which governs nuclear interactions. In this talk I will discuss the use of Lattice QCD as a tool for numerically calculating matrix elements relevant for experimental BSM searches. I will use neutrinoless double beta decay, which, if observed, could offer an explanation for the matter-antimatter asymmetry of the universe, as a key example.