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SUMMARY:Giant Fluctuations of Coulomb Drag - Dr Adam Price\, Quantum Syste
 ms and Nanomaterials Group\, School of Physics\, University of Exeter
DTSTART:20110207T141500Z
DTEND:20110207T160000Z
UID:TALK29623@talks.cam.ac.uk
CONTACT:afw24
DESCRIPTION:In a system where two parallel conducting layers are located i
 n close proximity to each other\, an effect called Coulomb drag can be obs
 erved. This Coulomb drag is a direct manifestation of electron-electron in
 teractions\, where momentum is transferred from electrons in a current-car
 rying ‘active’ layer to electrons in the ‘passive’ layer. The drag
  resistance is a measure of the strength of this effect\, and has been use
 d extensively as a sensitive probe of the electron-electron interactions. 
 \n\nMore recently it was predicted that at low temperatures mesoscopic flu
 ctuations in the drag resistance would occur\, similar to those seen in co
 nventional single-layer systems [1\,2]. However\, it was shown that in con
 trast to conventional systems\, the fluctuations in the Coulomb drag could
  exceed the average value\, resulting in a negative drag resistance.\n\nI 
 will discuss our measurements of these mesoscopic fluctuations of the Coul
 omb drag\, in which we confirmed the presence of a negative drag resistanc
 e for certain values of carrier-density and perpendicular magnetic field. 
 Furthermore\, we observed an unanticipated enhancement of these fluctuatio
 ns\, which we ascribed to the important contribution from fluctuations in 
 the local density of states [3\,4] in our samples.\n\nReferences:\n[1] B. 
 N. Narozhny and I. L. Aleiner\, Phys. Rev. Lett. 84\, 5383 (2000).\n[2] B.
  N. Narozhny\, I. L. Aleiner\, A. Stern\, Phys. Rev. Lett. 86\, 3610 (2001
 ).\n[3] A. S. Price\, A. K. Savchenko\, B. N. Narozhny\, G. Allison\, D. A
 . Ritchie\, \n     Science 316\, 99 (2007).\n[4] A. S. Price\, A. K. Savch
 enko\, D. A. Ritchie\, Phys. Rev. B 81\, 193303 (2010).\n
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Department of Physics
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