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SUMMARY:Probing the normal and superconducting state electronic structure 
 of iron-pnictide superconductors - Tony Carrington\, University of Bristol
DTSTART:20100414T101500Z
DTEND:20100414T111500Z
UID:TALK23815@talks.cam.ac.uk
CONTACT:Michael Sutherland
DESCRIPTION:In this talk I will give an overview of our research into the 
 newly\ndiscovered iron-based superconductors.  The work has two main threa
 ds.\n(1) Investigation of the normal state electronic structure using high
 \nfield measurements of the de Haas-van Alphen effect\, and (2)\nInvestiga
 tion of the anisotropy of the superconducting energy gap using\nmeasuremen
 ts of magnetic penetration depth.  I will argue that the\npenetration dept
 h data suggest that there are two competing pairing\nchannels in these mat
 erials  - one which produces a gap with nodes and\nanother which produces 
 a fully gapped (nodeless) pairing state.  It\nseems that these different p
 airing channels can both produce high Tc\nsuperconductivity.  The dHvA dat
 a will be compared to band-structure\ncalculations to reveal the extent of
  the many body corrections.  For the\nseries BaFe_2(As_(1-x)P_x)_2 we are 
 able to track the changes in the\nFermi surface parameters as the composit
 ion is tuned towards that\noptimal for superconductivity.  As the maximal 
 Tc is approached we find\nboth the electron and hole Fermi surfaces shrink
  and the effective mass\nincreases strongly. This data suggests a direct q
 uantitative link\nbetween spin-fluctuation induced changes to the normal s
 tate and the\nmicroscopic superconducting pairing mechanism.\n
LOCATION:TCM Seminar Room
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