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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-2531
DTSTART:20120119T160000Z
DURATION:PT1H0M0S
DTSTAMP:20260315T013815Z
LAST-MODIFIED:20120117T165354Z
LOCATION:5310 Chamberlin
SUMMARY:Nematic order and magnetism in the high-temperature iron-based
  superconductors\, R. G. Herb Condensed Matter Seminar\, Rafael Fernan
 des\, Columbia University
DESCRIPTION:The recent discovery of iron-based compounds displaying su
 perconductivity at nearly 60K opened a new direction in the research o
 f high-temperature superconductors. Much of the interest lies in under
 standing not only their superconducting pairing mechanism\, but also t
 heir normal state properties. In this talk\, I will show that emergent
  Ising-nematic degrees of freedom are present in these systems over wi
 de temperature and doping ranges\, fundamentally affecting their macro
 scopic properties and explaining several behaviors observed experiment
 ally. Starting from a microscopic electronic model\, I will demonstrat
 e that the nematic state has magnetic origin\, and is associated with 
 a spontaneous tetragonal symmetry-breaking. I will discuss the phase d
 iagrams resulting from this model\, and how the elastic properties are
  affected by nematic fluctuations. I will also show that the scatterin
 g of electrons by impurities and by spin fluctuations in the nematic p
 hase leads to an anisotropy in the resistivity\, whose sign changes fr
 om electron-doped to hole-doped compounds. 
URL:https://www.physics.wisc.edu/events/?id=2531
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