Fall 2017

Organizer : Dr. Drew Sills and Dr. Yi Hu

• • Date: Thursday, November 30

  • Time: 2:00 – 3:00 PM

  • Location: Math/Physics Bldg 3001

  • Speaker: Dr. Jason Liu (Georgia Southern University)

  • Title: Optical Detection of Magnetization Dynamics in Ferromagnetic Nanostructures

  • Abstract: Magnets are everywhere in our modern-day lives. They're in our phones, cars, and computers. Recent advances in magnetic technology has enable smaller, faster, and more reliable electronic devices. An example would be magnonic devices, which uses a type of magnetic excitation, called spin waves, to transfer information. In this talk, I will review the basic physics of magnetization dynamics. I will show results from measuring spin waves in patterned magnetic structures using Brillouin light scattering. I will also discuss results using the optically detected magnetic resonance properties of nitrogen-vacancy (NV) centers. NV magnetometry is a relatively new technique that exploits an atomic defect in diamonds and has the potential to measure magnetic fields that are orders of magnitude smaller than the Earth's magnetic field.

  • Date: Thursday, November 16

  • Time: 3:15 – 4:15 PM

  • Location: Math/Physics Bldg 3314

  • Speaker: Dr. Yuanzhen Shao (Georgia Southern University)

  • Title: Regularity of the Interface of a Thermodynamically Consistent Two-Phase Stefan Problem

  • Abstract: We study the regularity of solutions to a thermodynamically consistent two-phase Stefan problem with or without kinetic undercooling. It is shown that the free interface of the problem immediately becomes smooth or even analytic jointly in time and space, provided the initial surface satisfies a mild regularity assumption. The proof is based on a combination of a family of parameter-dependent dffeomorphisms, Lp-maximal regularity theory, and the implicit function theorem.

  • Joint talk with Department Colloquium

  • Date: Friday, November 10

  • Time: 3:30 – 4:30 PM

  • Location: Math/Physics Bldg 3314

  • Speaker: Dr. Gieri Simonett (Vanderbilt University)

  • Title: Moving Surfaces in Geometry and Physics

  • Abstract: Moving surfaces are ubiquitous in many areas of mathematics and the applied sciences. In this talk I will first introduce some well-known geometric evolution equations, and then proceed to more complicated models that describe the motion of fluids and of materials that can undergo phase transitions.

  • Joint talk with Computational Sciences Seminar and Statistics Seminar

  • Date: Wednesday, November 8

  • Time: 4:00 – 4:50 PM

  • Location: Math/Physics Bldg 2314A

  • Speaker: Robert Schneider (Emory University)

  • Title: Number Theory in Statistical Physics: Using Integer Partitions to Compute Expected Values

  • Abstract: The set of integer partitions— i.e., all possible ways to add numbers to get other numbers— ripples with beautiful patterns and relations that delight number theorists. And much like the integers themselves, partitions serve to index important discrete sets, such as conjugacy classes of the symmetric group in abstract algebra and, via statistical mechanics, states of finite physical systems in chemistry, quantum theory and even black hole physics. One might wonder: to what extent are theorems from number theory part of the fabric of nature? In fact, purely partition-theoretic considerations lead to concrete predictions of observable events. We discuss the explicit computation of expected values in systems indexed by partitions using the classical Faà di Bruno's formula and the recently introduced q-bracket of Bloch and Okounkov connected to modular forms.

  • Joint talk with Department Colloquium

  • Date: Friday, November 3

  • Time: 3:30 – 4:30 PM

  • Location: Math/Physics Bldg 3314

  • Speaker: Dr. Matthew Creek (Assumption College)

  • Title: Global Well-Posedness Results for Generalizations of the Nonlinear Sigma Model

  • Abstract: The classical nonlinear sigma model of Gell-Mann and Levy, which describes interactions between nucleons and pions, has given rise to several generalizations. Among these are the Skyrme and Faddeev models, which are quasilinear generalizations that admit topological solitons. The global well-posedness of the equations of motion associated with these models has been studied intensely in recent years, in both the small- and large-data regimes. In this presentation, I shall discuss a novel technique which has been instrumental in helping to prove several large-data global well-posedness results for the Skyrme and Faddeev models. I shall also discuss current efforts in which I try to understand and apply this technique more broadly in order to unite these several results under the rubric of one more general result.