Emanuel Katz (Boston University)

Title: TBA

Abstract: TBA

Gang Cao (University of Colorado Boulder)

Title: TBA

Abstract: TBA

Ji Wang (Ohio State University)

William Gannon - University of Kentucky

Title: Neutron Diffraction and Magnetotransport Studies of the Candidate Weyl Semimetal CeGaGe

Abstract: The RXZ (R = rare-earth, X = Al or Ga, Z = Si or Ge) family of materials is thought to crystallize with symmetry described by the noncentrosymmetric I41md space group. Band structure calculations of many members of this family predict Weyl semimetal behavior with topologically protected surface states. 

When the rare-earth ions carry a magnetic moment, these materials also exhibit magnetic order, allowing Weyl states above the ordering temperature and enabling studies of the interplay between Weyl quasiparticles and magnetic excitations below it. 

The magnetic order in these compounds is often nontrivial and tied precisely to material composition [1, for example]. The compound CeGaGe belongs to this family. Depending on crystal growth conditions, we find that samples can undergo a subtle structural transition to another noncentrosymmetric structure, with symmetry described by space group P43, at temperatures above about 100 K [2]. 

Regardless of low-temperature structure, all samples show a clear transition to a magnetically ordered state at Tc = 5.5 K [2,3]. I will present our ongoing neutron diffraction studies characterizing the crystal and magnetic structures of CeGaGe with varying stoichiometry, revealing a complex relation between composition, ferromagnetic order, and chiral ordered states. I will also discuss our magnetotransport measurements and their relation to these ordered magnetic states.

[1] X. Yao et al., Phys. Rev. Lett. 136, 086702 (2026).
[2] L. Scanlon et al., Phys. Rev. B 111, 184102 (2025).
[3] D. Ram,  et al, Phys. Rev. B 108, 024428 (2023).

Dr. Jiayi Sun (University of Kentucky)

Sajia Shahrin Neha, Pre-Doctoral Researcher (University of Kentucky)

Title:

Hidden Gems: How Nature Builds the Densest Star Clusters

Abstract:

Most stars today form in modest groups, but a small fraction of star formation proceeds in a far more extreme mode, assembling more than10,000 Msun of stars within space of a few parsecs. The resulting young massive star clusters (YMCs) are natural laboratories for understanding the interplay among gravity, turbulence and energetic radiation and the nearest analogs to the conditions under which most stars in the universe were born. We will describe a multiwavelength study of YMCs forming near the centers of two nearby spiral galaxies. 

With millimeter-wave and radio observations taken with the Atacama Large Millimeter Array (ALMA) and the Very Large Array (VLA), we found more than 70 YMC candidates through their thermal dust and free-free emission, more than tripling the sample size compared to previous works. We place each source in an evolutionary sequence from starless cores to dust embedded proto-clusters and to exposed clusters with strong ionizing radiation. With an adapted version of the ergodic argument, we convert source counts into the durations of all evolutionary stages, thereby constraining the cluster assembly and feedback timescale.

Our mass and size estimates also suggest that these YMCs have high volume densities, surface densities and escape velocities, which explain the high star formation efficiency in such extreme environments. Next-generation facilities such as ALMA's Wideband Sensitivity Upgrade and the ngVLA will extend this census across the entire local galaxy population.

Dr. Joseph Straley (University of Kentucky)

Title: How to Explain Global Warming In Just a Few Words

Abstract: I believe that this is not an issue to leave to "the experts" --  we're teachers of physics, and this is physics.   I'll present the minimal explanation.

Dr. Erik Henriksen, Washington University, St. Louis

Title:  Thermal transport in atomically thin materials

Abstract: Inspired by the potential to study quantum spin liquid-related phenomena in unusual magnetic materials, we are developing methods to measure thermal properties of single- and few-layer atomically thin materials, as well as thicker flakes. We will briefly introduce the Kitaev-type quantum spin liquid and the most promising material candidate at the moment, a-RuCl3, and then review some recent experimental progress including a surprisingly large and useful charge transfer when a-RuCl3 is placed in proximity to other materials. The remainder of the talk will cover our latest work on a technique to simultaneously measure the thermal conductivity and specific heat in suspended quasi-2D systems, starting with SiN membranes and moving on to flakes of a-RuCl3, hexagonal boron nitride, and also the antiferromagnet FePS3.

Dr. Deborah Ferguson, The University of Rhode Island

Title: Using Numerical Relativity for Gravitational-Wave Astronomy

Abstract: Ten years ago, the Laser Interferometer Gravitational-Wave Observatory detected gravitational waves from merging black holes for the first time. In the 10 years since, we've observed nearly 400 more binary mergers. This is only expected to improve as next-generation detectors, such as the Laser Interferometer Space Antenna, are already under development and promise even higher sensitivities. 

Detecting and characterizing these signals relies upon having a strong understanding of the expected gravitational waves from such systems. This understanding is provided by numerical relativity, which computationally solves Einstein's equations. In this talk we'll discuss the current and future state of gravitational-wave astronomy as well as how we use numerical relativity to enable such observations.

Dr. Steve Turley, Brigham Young University

Title: Using Physics in Unusual Places

Abstract: I would sometimes tell students that if they didn’t know what major to choose, they should choose physics because it is the basis of everything else. While this is perhaps a bit overstated, it is valuable for faculty members to keep in mind that most of our students will have careers that look different than our academic pursuits. 

I will discuss physics applications I have found outside typical academic settings. As part of an exotic weapons development program, I participated in some of the early development of ultra-cold atoms, the optical Stern-Gerlach Effect and the development of a coherent Lyman-alpha source. While studying efficient ways to compute radar cross sections of stealthy targets, I not only used my background in electromagnetic theory but also some machinery from General Relativity and quantum mechanics. 

Work on measuring lifetimes of parts in ion thruster satellite engines used results from astrophysics. After a 25-year academic career, I have been assisting as a volunteer at FamilySearch, an international nonprofit collaborative genealogical platform. To my surprise and delight, I’ve found ways my physics background can be applied to problems in computerizing and indexing genealogical records, preserving privacy, optical character recognition and matching records to family trees.

Dr. Sang Mo Yang, Sogang University, South Korea

Title: Ferroelectricity at the Nanoscale: Emerging Materials and Local Probes

Abstract: Ferroelectricity on the nanoscale has been the subject of considerable interest in condensed matter physics for over half a century. Beyond its fundamental importance, ferroelectricity provides essential functionality for advanced electronic devices, including nonvolatile memories, field-effect transistors and tunnel junctions. 

However, conventional perovskite-based ferroelectric oxides (e.g., Pb(Zr,Ti)O3) face significant challenges in achieving device performance that can compete with current dynamic random-access memories and flash memories. Over the past decade, novel ferroelectricity has been discovered in new material systems, including fluorite-structured HfO2-based thin films, two-dimensional (2D) van der Waals (vdW) materials and 2D perovskite halides. These discoveries have brought about a renaissance in the ferroelectric research community. 

In this colloquium, I will present our group’s recent efforts to investigate and understand ferroelectricity across these emerging material platforms [1] using various scanning probe microscopy techniques.
[1] T. H. Jung et al., “Spatially Resolved Observation of Ferroelectric-to-Paraelectric Phase Transition in a Two-Dimensional Halide Perovskite,” Advanced Materials 37, 2506270 (2025)