Tuesday, March 07, 2023

APS March Meeting 2023, Day 1

Ahh, Las Vegas.  I will say, I think every APS March Meeting from now on should have a giant Ferris wheel right by the registration lobby.   

Here are a few highlights from what I saw after I arrived around lunchtime today:

  • Given some of my current research, I spent a fair bit of time at the invited session about strange metals today.   All of the talks that I saw were very strong.  Andrew MacKenzie spoke about recent measurements of the Lorenz number in such materials (particularly Sr3Ru2O7) and made a persuasive case that strange metals do look different in their temperature-dependent thermal conductivity, because of very strong electron-electron scattering.  This is discussed in this recent review article.  
  • In the same session, Brad Ramshaw showed very pretty angle-dependent magnetoresistance data on Nd-LSCO, an archetypal cuprate, arguing that the whole data set can be modeled very well assuming conventional quasiparticles and Boltzmann equation analysis (albeit with a funky combination of temperature-independent anisotropic scattering and strongly temperature dependent isotropic scattering).  His postdoc Gaël Grissonnanche expanded on this and looked at how such a model can also reproduce the linear-in-B magnetoresistance in this system.
  • At the McGroddy Prize session, James Hone gave a very nice overview of the impressive body of work from Columbia over the years on all of the stackable van der Waals materials.  Some particular recent highlights included: (1) using deliberately oxidized WSe2 (into WOx) as a low-disorder, very high workfunction material that modulation dopes holes when stacked on a target layer of interest; (2) Using vdW material ferroelectricity to modulate superconductivity in MoTe2; in-progress work using an AFM + an hBN "handle" to bend a graphene "noodle" to get continuously tuned, clean moiré potentials; and electrostatically actuated sliding motion of monolayer vdW material.
Hopefully crowd control will be a bit better tomorrow.  The hallways seemed narrower than at past meetings, very crowded, and the site would benefit from more places to sit and have conversations.

2 comments:

Ross H. McKenzie said...

The angle-dependent magnetoresistance data described by Brad Ramshaw has been around for three years. Theorists in his own department wrote a critique, published in PRB,
https://journals.aps.org/prb/abstract/10.1103/PhysRevB.105.125105
Coauthors include Patrick Lee and Senthil.
Yet the Nature Physics paper you link to does not even mention this. Did Ramshaw mention this in his talk?

These two papers and subtleties associated with interpreted angle-dependent magnetoresistance are discussed at length in this blog post

https://condensedconcepts.blogspot.com/2022/01/angle-dependent-magnetoresistance-as.html

Although these authors assume a three-dimensional Fermi surface or claim to observe one, almost all these materials are in the regime where only a two-dimensional Fermi surface is well-defined.

Douglas Natelson said...

Hi Ross, in the presentation, the two-dimensionality of the Fermi surface (in the sense of deep anisotropy) was emphasized, but the Lee/Senthil paper was not discussed.