- There is a lot of interest in trying to capture optical energy (e.g., from the sun) and not waste so much of it. Plasmons in metals provide one way of converting a photon into electron-hole excitations in a metal - the trick is to then do something useful with those "hot" electrons and holes. Lisa Krayer spoke about a clever approach of putting a metal film grating on the back of a Si photovoltaic system, to grab photons too low in energy for the Si itself into plasmons, and then kick "hot" electrons back into the Si. As an added bonus, the optical properties of the Si (high index of refraction) end up implying that the grating can capture light over a much larger range of incident angles than if the grating was on the front side. Similar in spirit, Prinaha Narang spoke about theoretical modeling of the electrons in these and similar plasmonic structures, with an eye toward manipulating (through geometry) the momentum and energy distributions of the hot electrons and holes.
- Hsin-Zon Tsai gave an interesting talk about using an underlying gate electrode to change not just the charge density in a layer of graphene, but also to manipulate the amount of charge on a molecule (called F4TCNQ) tethered to the graphene. Measuring by scanning tunneling microscope, Tsai and coworkers showed that the highest occupied molecular level always sat lower in energy than the Dirac point of the graphene, and made a nice argument in support of this involving image charges.
- In his talk in honor of receiving the Adler Prize, Harry Atwater gave a nice overview of his group's plasmonics efforts, including a discussion of their concept of the plasmoelectric effect: Illuminating a plasmonic object in an environment where it can gain or lose charge can drive charge transfer, as explained here.
- We are used to employing ferromagnets in electronic devices. Maxim Tsoi gave a very clear talk about some remarkable work using antiferromagnets, both for magnetoresistive devices and for the manipulation of and by spin currents. The next talk in that session, by Wei Zhang, described recent work where antiferromagnetic alloys were used as sources of spin currents. Very pretty stuff.
- I also caught part of the session where various historians of science (and a noted blogger) critiqued/commented on Steven Weinberg's latest book, with Weinberg in the room to offer rebuttal.
Monday, March 14, 2016
APS March Meeting, day 1
First, hat tip to Chad Orzel for this article, and ZapperZ for his. While condensed matter physics is harder to describe to a general audience, it's shaped your everyday life far more than string theory or neutrino oscillations. We as a community need to do a better job getting that across, as well as the wonder that some of these topics inspires. Interesting talks that I saw today (aside from those of my group members, of course):
Posted by Douglas Natelson at 9:13 PM