DOE Experimental Condensed Matter Physics PI Meeting 2025 - Day 3 and wrap-up

 A few more interesting tidbits from the concluding half-day of the DOE ECMP PI meeting:

• Dmitri Basov showed some of the remarkable experiments enabled by layers of MoOCl2, which in the IR is an intrinsically hyperbolic optical material.  This material has unusual plasmonic properties considering its high resistivity.  These include peculiar cavity effects such as modifying superfluid density of a proximally coupled superconductor.
• Leonid Butov explained some remarkable evidence for superfluidity of indirect excitons excited in the moire bilayer of MoSe2/WSe2.  Low temperature mean free paths of these objects can exceed hundreds of microns (!).
• Cui-Zu Chang showed evidence that truly stoichiometric FeTe is actually a superconductor with a critical temperature of about 13.5 K, rather than the usual thinking that it is an antiferromagnetic metal. Apparently an extra 2% of interstitial iron is enough to kill superconductivity and induce AFM order.
• James McIver presented an example of how nonlinear optical effects in an optically driven (Floquet) Weyl semimetal seem to vary linearly with driving field - anomalously strong.
• Dmytro Bozhko showed a really neat technique, using Brillouin light scattering to map out the dispersion of phonons and magnons in YIG, and to extend this approach with a special hollow-core optical fiber to low temperatures with the motivation of probing magnon superfluidity in a particular antiferromagnetic insulator.
• Ray Ashoori used his characteristically pretty quantum capacitance measurement technique to examine the density+displacement field+magnetic field phase diagram of 5-layer rhombohedral graphene, revealing some surprising fractional Chern insulator states.
• Claudia Ojeda-Aristizabal discussed some mesoscopic transport measurements in bilayer graphene, where an adsorbed layer of spin-containing CuPc molecules seems to affect both decoherence and the trigonal warping contribution to it (related to intervalley scattering). 
• Feng Wang and You Zhou both discussed recent measurements looking at Wigner crystals and their properties in 2D TMDs, through a variety of means.
• Liuyan Zhao showed some very rich physics obtained in studies that moiré stack bilayers of the van der Waals insulating magnet CrI3.  

Unfortunately I missed the last talk because of the need to head to the airport.  Overall, the meeting was very good.  Program PI meetings can tend to become less about telling coherent scientific stories and more about trying to show everything someone has done in the last three years.  This meeting avoided that, with clear talks that generally focused on one main result, and that made it much more engaging.  As good as tools for virtual gatherings have become, there really is no substitute for an in-person event when you can just talk to someone by the coffee about some new idea.