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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-2299
DTSTART:20111003T183000Z
DURATION:PT1H0M0S
DTSTAMP:20240319T020457Z
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 Hc2(T) which often extrapo
late to Hc2 > 100 Tesla at low temperatures for some FBS. T
he materials features of FBS and the multiband s+/- pairing
symmetry with the sign change of the order parameter on different she
ets of the Fermi surface can significantly increase Hc2(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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