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SUMMARY:Organic  magnetoresistance – Search for the perfect defect - Pro
 f. Bert Koopmans\, Department of Applied Physics\, Eindhoven University of
  Technology\, Netherlands
DTSTART:20131001T133000Z
DTEND:20131001T143000Z
UID:TALK47346@talks.cam.ac.uk
CONTACT:Dr. Girish Lakhwani
DESCRIPTION:Organic spintronics aims at new device functionality by combin
 ing the field of spintronics with that of organic electronics. The field c
 overs a broad spectrum of phenomena and devices\, including spin-valves ba
 sed on hybrid organic-ferromagnetic metal junctions\, as well as intrinsic
  magnetoresistance effects in ‘ordinary’ OLEDs. Such effects can be su
 rprisingly large (> 20%) at room temperature and applying magnetic fields 
 of just a few millitesla. Recent work even reports on 1000’s of percents
  in molecular wires\, while effects at ultra-small fields (< 1 mT) and a d
 ependence on the orientation of the magnetic field have been observed as w
 ell\nWithin this presentation it will be shown how different reactions bet
 ween spin carrying carriers in the presence of local hyperfine fields can 
 explain the effect – very similar to spin-chemical reactions suggested t
 o underlie the navigation ability of migratory birds in the Earth’s magn
 etic field. In organic devices\, the final manifestation of the effect is 
 the result of a subtle interplay between microscopic mechanisms and device
  physics. In recent work on polymer-fullerene blends we have disentangled 
 the various contributions [1]. Furthermore\, we found that trap sites – 
 which are generally considered detrimental for device performance – migh
 t be crucial in their explanation. Thus\, at present\, the quest is for th
 e perfect defect\, i.e. the most ideal trap site to boost the magnetic fie
 ld dependence for future applications.\n\n[1] P. Janssen\, M. Cox et al.\,
  Nature Communications 4\, 2286 (2013)
LOCATION:Microelectronics Research Centre (MRC) Seminar Room\, Cavendish L
 aboratory\, Department of Physics
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