Events on Thursday, April 16th, 2026
- R. G. Herb Condensed Matter Seminar
- Anomalous Hall effect and piezomagnetism in altermagnets
- Time: 10:00 am - 11:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Maxim Khodas , Hebrew University of Jerusalem
- Abstract: I begin with a general exposition of altermagnetism, introducing the two-dimensional Lieb lattice as the simplest realization of this novel magnetic phase. The anomalous Hall effect arising from altermagnetic order and spin–orbit interaction is discussed based on symmetry considerations and illustrated with several examples. A comparison between the magnetic point-group and spin-space-group formulations is presented, demonstrating that the Berry-curvature singularity at nodal lines gives rise to a linear, non-analytic scaling of the intrinsic Hall conductivity with spin–orbit coupling. In the second part of the talk, I consider the extrinsic anomalous Hall effect in the limit of large exchange splitting. In materials with a finite Dzyaloshinskii–Moriya–type interaction, the extrinsic contribution remains essential even in the clean limit. This naturally separates altermagnetic symmetry classes into two distinct categories, differing from other classifications found in the literature.
- Host: Alex Levchenko
- Astronomy Colloquium
- Single-lined Eclipsing Binary Stars: A Stellar Astronomy Multi-Tool
- Time: 3:30 pm - 4:30 pm
- Place: 4421 Sterling Hall
- Speaker: Prof. Daniel Stevens, UMN-Duluth
- Abstract: Precisely and accurately measured stellar properties such as mass and radius are important for a wide range of science cases, from characterizing nearby exoplanets to inferring properties of distant galaxies. Double-lined eclipsing binary stars (DLEBs) have long been the gold standard for making such measurements, as the two similar-luminosity stars’ individual masses and radii can routinely be measured to percent-level precision. By combining space-based observations from the TESS and Gaia space telescopes with archival datasets, it is now possible to measure fundamental stellar parameters precisely and accurately for single-lined EBs (SLEBs), in which only the more luminous star’s spectrum is seen. I will summarize the advantages of studying SLEBs for specific science cases, focusing on recent efforts by my research group and others to resolve the longstanding problem of radius inflation in low-mass stars. I will also highlight a few “superlative” SLEB discoveries and their potential for probing stellar physics across the HR diagram. I will discuss the obstacles we have encountered to characterize SLEBs to percent-level precision and accuracy, then preview the near-term prospects for overcoming them.
- Host: Thomas Beatty