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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-2008
DTSTART:20110225T220000Z
DURATION:PT1H0M0S
DTSTAMP:20260414T004043Z
LAST-MODIFIED:20110221T142342Z
LOCATION:2241 Chamberlin Hall (coffee at 3:30 pm)
SUMMARY:Led by the Nodes: Forging an Understanding of Fe-Based Superco
 nductors\, Physics Department Colloquium\, Peter Hirschfeld\, Universi
 ty of Florida
DESCRIPTION:The new Fe-based superconductors have occasioned considera
 ble excitement because transition temperatures are high\, and it is ho
 ped that comparisons to cuprates will lead to new insights into the es
 sential ingredients for high temperature superconductivity. I will bri
 efly review some similarities and differences to the cuprates\, focuss
 ing first on normal state magnetic and transport properties. In this r
 espect some of the remarkable properties of these systems can be under
 stood by consideration of the multiorbital character of the multisheet
 ed Fermi surface. Next\, I will review what is known about the superco
 nducting state\, explaining the basis for the near-consensus that all 
 pnictide materials display spin singlet\, orbital s-wave symmetry. Som
 ewhat more controversial are differing reports on gap structure sugges
 ted by different experimental probes on different materials\, includin
 g varying claims of gap nodes or fully gapped behavior. I will argue t
 hat such a diversity of gap structures\, unexpected based on cuprate i
 ntuition\, is characteristic of systems with s-symmetry and the unusua
 l band structure of the Fe-based superconductors. They should\, and do
 \, display an "intrinsic sensitivity" to small perturbations of electr
 onic structure. I review what is to be expected in this regard from sp
 in fluctuation theories\, where multiorbital effects are found again t
 o play a crucial role. Finally\, I will discuss how 3-dimensionality i
 nfluences superconducting order. 
URL:https://www.physics.wisc.edu/events/?id=2008
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