The March Meeting continues. Other topics that seem relatively hot (based on the number of abstracts) compared to previous years include thermoelectrics and ultracold gases and fluids. The latter are really at the border between condensed matter and atomic/molecular/optical physics, and it's interesting to see the merger of the two disciplines. While the ultracold gases provide an exquisitely clean, tunable environment for studying some physics problems, it's increasingly clear to me that they also have some significant restrictions; for example, while optical lattices enable simulations of some model potentials from solid state physics, there doesn't seem to be any nice way to model phonons or the rich variety of real-life crystal structures that can provide so much rich phenomenology.
Anyway, I saw some very pretty talks today. Taking the prize for coolest graphics in a presentation were definitely two talks from an invited session on Kondo physics. The first was by Andreas Heinrich, giving an overview of the IBM Almaden's use of scanning tunneling microscopy to examine magnetic anisotropy and Kondo physics on the single atom level. The second was by Hari Manoharan of Stanford, who showed around three experiments, the most elegant of which involved using STM of magnetic atoms to demonstrate that sometimes it's possible to really extract phase information about superpositions of quantum states. Basically he showed that one could make a designer system (an elliptical corral that confines the Cu(111) surface states) and then use STM spectroscopy based on the Kondo properties of Co atoms on the Cu(111) surface to identify specific superpositions of the eigenstates of that corral.
Another interesting series of talks took place in a session that I organized, where Lindsay Moore of the Goldhaber-Gordon group at Stanford discussed some recent studies of the so-called "0.7 anomaly". In 2d electron gas, it is possible to use gates to create a 1d constriction for a small number of electronic modes. This is called a quantum point contact (QPC). In zero magnetic field, as the point contact is pinched off the conductance of the QPC drops in quantized steps of 2e2/h until it falls to zero. The 0.7 anomaly is the appearance of an extra plateau in the conductance at around 0.7 x 2e2/h. People have been bandying about possible explanations for this feature for a while now, and finding new probes to apply is a popular tactic. The following contributed talk was by Alex Hamilton from UNSW, who had looked at the 0.7 anomaly in 2d hole systems. The holes have strong spin-orbit scattering effects that, through the study of response to applied magnetic fields, allow one to demonstrate convincingly that the 0.7 anomaly clearly has some mechanism related to spin. Nice.