Thursday, May 22, 2014

Workshop on structural and electronic instabilities in oxide nanostructures

I've spent the last two days at a fun "Physics at the Falls" workshop at the University of Buffalo.  It's been cool learning about the impressive variety of physics at work in these systems.  A few takeaways:
  • With enough stainless steel and high tech equipment you can grow (and in situ characterize with everything from electron diffraction to photoemission, angle-resolved and otherwise) just about anything these days!
  • There's a lot of pretty work getting done growing epitaxial complex oxides down to the single unit cell level, and a lot of accompanying extremely high resolution transmission electron microscopy.
  • Untangling thermal effects from optical effects in nonequilibrium experiments can be tricky.  Interesting to see that lower energy photons can be more efficient at kicking systems from one phase to another than photons much more energetic than any energy gap.
  • There does seem to be some convergence on understanding LAO/STO oxide heterojunctions.
  • We still don't understand superconductivity in strontium titanate, even though it's been known for decades.
  • Orbitals really matter, when you are dealing with relatively localized electrons.
  • Niagara Falls is very impressive!


barabogi said...

Thanks for sharing of the workshop,

Can you give some hint about "some convergence on understanding LAO/STO"? Polar nature? or localized electron? or defects? or new one?

Dmytro Solonenko said...

Could You specify the role of stainless steel (from the first takeaway)? It sounds to me a bit untrue since stainless steel is not appropriate material for any kind of depositions, thermal treatment etc.

Douglas Natelson said...

Barabogi, this isn't my focus, so I hope I don't mis-state anything. That said, in brief: polar catastrophe avoidance through band bending leads to the 2d gas; oxygen vacancies are important to worry about, esp in terms of magnetism; ferroelasticity in STO below 105K must be dealt with properly; there seems to be some non-defect-related magnetism related to the Lifshitz transition (that is, cross-over from light, high mobility d band to including a much heavier, localized d band).

Dmytro, that was just my joking way of referring to big ultrahigh vacuum chambers. They're very impressive looking, particularly if you combine growth chambers with characterization tools.