Thursday, March 07, 2019

APS March Meeting wrapup

I spent the lion's share of today talking w/ my collaborators.  This was great scientifically, but meant that I only went to a couple of talks. 

  • This one was pretty slick.  If you look at the conduction properties of a Josephson junction as a function of magnetic field through it, you see a Frauenhofer pattern as a function of the enclosed flux (see this pdf, fig 2).  In principle, taking the inverse Fourier transform of this should reveal the real-space current distribution as a function of the distance along the width of the junction.  This group made Josephson junctions using oriented thin pieces of WTe2.  When the current flowed along one direction, they found that the Josephson current was mostly flowing near the edges of the strip of material.  When current flowed along a different direction in the plane, the current distribution was much more uniform.  
  • Similarly evocative, this talk presented work using magnetic focusing plus scanning gate microscopy plus collimating contacts to look at the real-space paths of electrons in a graphene-hBN bilayer w/ a Moire superlattice.  They could then infer the shape of the Fermi surface in momentum-space, confirming that the Moire superlattice results in a roughly triangular (miniband) Fermi surface.  Cooler than my jargon-heavy description sounds.
  • I greatly regret that I was unable to attend the invited session in honor of Millie Dresselhaus.  If one of my readers who did make it could please describe it in a comment, I'd appreciate it.
  • One other random note:  I did actually speak to the APS person who was in charge of the trade show, and I asked what the heck was up with the two weird "pain relief" booths, which seemed borderline late-night-infomercial/much more like something you'd see at a cheesy shopping mall.  This was apparently an experiment in allowing local vendors in, and it sounds very unlikely that it'll ever happen again.  
If I missed a big story from the meeting, please let me know in the comments.


Anonymous said...

Not related to the post. I shall like to know how do you choose the direction of your research? What approach do you follow for sample fabrication, multiple samples or focussed on a single sample. How do you decide on which characterisations to go for?

Douglas Natelson said...

Hi Anon, that's a big question. In the broadest sense, it's important to read the literature and figure out which scientific open question interests you and is something that you might credibly be able to address. There is some amount of strategy in this, in that jumping into an already crowded problem only makes sense if you have some competitive advantage or unique approach to bring to bear. For example, I find a lot of quantum computing/quantum engineering research very interesting (e.g., implementing models of solid state Hamiltonians via superconducting resonators and tunable effective photon-photon interactions), but there are other people who have been working on this stuff for years, and it's hard to believe that I could catch up and be competitive. Once you have the problem, you need to think about how you can best get answers. My history in nano stuff has taught me that you have to be extremely careful in drawing conclusions from a single sample of anything.

Anonymous said...

Thank you for your reply. I see a lot of papers in nanoscience where a group makes an exotic kind of nanostructure, do some characterisations (Raman, xps etc) but I do not understand if research is only about publishing. Thousands of publications that report on electrical, optical properties of nanostructures.

Like I feel in plasmonics, people keep making new kind of nanostructures and keep doing their electromagnetic studies but I do not know how fruitful that research is going to be in the long term from an actual device point of view.

Nowadays I see a lot of publications that contain ambiguous statements. Probably, there is a race to be first or to bag a project, to get the funding which I certainly don't like. Don't know what's the hurry. Slow and steady but good publications what I believe in even if the number is less but that I think will be an Ideal world which don't exist now.