Events on Thursday, September 26th, 2024
- R. G. Herb Condensed Matter Seminar
- Electron Interactions in Rashba Materials
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Yasha Gindikin, University of Minnesota
- Abstract: We present a bunch of novel phenomena stemming from the pair spin-orbit interaction (PSOI), which does not rely on structure inversion asymmetry but instead arises from Coulomb fields of interacting electrons in materials with a strong Rashba effect. First, PSOI can induce p-wave superconducting order without the need for any mediators of attraction. Depending on the sign and strength of the PSOI coupling, two distinct superconducting phases emerge in 3D systems, analogous to the A and B phases observed in superfluid He3. In contrast, 2D systems exhibit p_x \pm i p_y order parameter, leading to the time-reversal-invariant topological superconductivity. Second, a sufficiently strong PSOI can induce ferromagnetic ordering. It is associated with a deformation of the Fermi surface, which eventually leads to a Lifshitz transition from a spherical to a toroidal Fermi surface, with a number of experimentally observable signatures. Finally, in sufficiently clean Rashba materials, ferromagnetism and p-wave superconductivity may coexist. This state resembles the A1 phase of He3, yet it may avoid nodal points due to the toroidal shape of the Fermi surface.
- Host: Alex Levchenko
- Astronomy Colloquium
- Things you should know about the Milky Way
- Time: 3:30 pm - 4:30 pm
- Place: 4421 Sterling Hall
- Speaker: Bob Benjamin, UW-Madison/UW-Whitewater
- Abstract: The last several years have seen truly remarkable advances in our understanding of the Milky Way Galaxy, from the identification of stellar streams and stellar ensembles associated with the formation history of our Galaxy to the identification and characterization of thousands of stellar clusters to the development of remarkably accurate three-dimensional maps of the distribution of interstellar dust out to three kiloparsecs from the Sun. A lot of these advances are due to the availability of high precisions parallaxes and proper motions from the ESA Gaia mission and VLBI BeSSeL program; large-scale programs of stellar spectroscopy and advances in angular resolution and sensitivity of surveys of the gas and star forming content of the Milky Way are also major contributing factors. The net effect of all of these changes is to turn the Milky Way into an excellent laboratory for studying the physical processes by which galaxies convert their gas into stars; this is occuring at the same moment as JWST observations are providing astounding external views of the same processes in nearby galaxies. In this colloquium, I will review the history of attempts to ascertain the structure of the Galaxy, highlight some of the key things we’ve learned about our Galaxy over the last few years, and provide a preview of things to come.
- Host: Melinda Soares-Furtado