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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-2299
DTSTART:20111003T183000Z
DURATION:PT1H0M0S
DTSTAMP:20260416T231859Z
LAST-MODIFIED:20110928T165849Z
LOCATION:5310 Chamberlin
SUMMARY:Fe-based superconductors at high magnetic fields\, R. G. Herb 
 Condensed Matter Seminar\, Alex Gurevich\, Old Dominion University
DESCRIPTION:Low carrier densities and short coherence lengths in the r
 ecently discovered semi-metallic Fe-based superconductors (FBS) can re
 sult in exotic behaviors at strong magnetic fields due to the interpla
 y of multiband superconductivity\, unconventional pairing symmetry and
  the Zeeman and orbital pairbreaking. I this talk I will give an overv
 iew of these effects\, particularly the anomalous temperature dependen
 cies of the upper critical field H<sub>c2</sub>(T) which often extrapo
 late to H<sub>c2</sub> > 100 Tesla at low temperatures for some FBS. T
 he materials features of FBS and the multiband s<sup>+/-</sup> pairing
  symmetry with the sign change of the order parameter on different she
 ets of the Fermi surface can significantly increase H<sub>c2</sub>(T) 
 and facilitate the Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) transition t
 o the state with a spatially modulated order parameter.  Small shifts 
 of the chemical potential upon doping of FBS can produce new small poc
 kets of the Fermi surface\, triggering the FFLO instability due to the
  Lifshitz transition. I will also discuss the effect of disorder\, par
 ticularly magnetic defects produced by α-particle irradiation.
URL:https://www.physics.wisc.edu/events/?id=2299
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