Friday, June 07, 2019

Round-up of various links

I'll be writing more soon, but in the meantime, some items of interest:

  • A cute online drawing utility for making diagrams and flowcharts is available free at
  • There is more activity afoot regarding the report of possible Au/Ag superconductivity.  For example, Jeremy Levy has a youtube video about this topic, and I think it's very good - I agree strongly with the concerns about heterogeneity and percolation. The IIS group also has another preprint on the arxiv, this one looking at I-V curves and hysteresis in these Au/Ag nanoparticle films.  Based on my prior experience with various "resistive switching" systems and nanoparticle films, hysteretic current-voltage characteristics don't surprise me when biases on the scale of volts and currents on the scale of mA are applied to aggregated nanoparticles.  
  • Another group finds weird effects in sputtered Au/Ag films, and these have similar properties as those discussed by Prof. Levy.  
  • Another group finds apparent resistive superconducting transitions in Au films ion-implanted with Ag, with a transition temperature of around 2 K.  This data look clean and consistent - it would be interesting to see Meissner effect measurements here.  
  • For reference, it's worth noting that low temperature superconductivity in Au alloys is not particularly rare (pdf here from 1984, for example, or this more recent preprint).   
  • On a completely different note, I really thought this paper on the physics of suction cups was very cute.
  • Following up, Science had another article this week about graduate programs dropping the GRE requirement.
  • This is a very fun video using ball bearings to teach about crystals - just like with drought balls, we see that aspects of crystallinity like emergent broken symmetries and grain boundaries are very generic.

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