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CATEGORIES:Semiconductor Physics Group Seminars
SUMMARY:Giant Fluctuations of Coulomb Drag - Dr Adam Price
 \, Quantum Systems and Nanomaterials Group\, Schoo
 l of Physics\, University of Exeter
DTSTART;TZID=Europe/London:20110207T141500
DTEND;TZID=Europe/London:20110207T160000
UID:TALK29623AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/29623
DESCRIPTION:In a system where two parallel conducting layers a
 re located in close proximity to each other\, an e
 ffect called Coulomb drag can be observed. This Co
 ulomb drag is a direct manifestation of electron-e
 lectron interactions\, where momentum is transferr
 ed from electrons in a current-carrying ‘active’ l
 ayer to electrons in the ‘passive’ layer. The drag
  resistance is a measure of the strength of this e
 ffect\, and has been used extensively as a sensiti
 ve probe of the electron-electron interactions. \n
 \nMore recently it was predicted that at low tempe
 ratures mesoscopic fluctuations in the drag resist
 ance would occur\, similar to those seen in conven
 tional single-layer systems [1\,2]. However\, it w
 as shown that in contrast to conventional systems\
 , the fluctuations in the Coulomb drag could excee
 d the average value\, resulting in a negative drag
  resistance.\n\nI will discuss our measurements of
  these mesoscopic fluctuations of the Coulomb drag
 \, in which we confirmed the presence of a negativ
 e drag resistance for certain values of carrier-de
 nsity and perpendicular magnetic field. Furthermor
 e\, we observed an unanticipated enhancement of th
 ese fluctuations\, which we ascribed to the import
 ant contribution from fluctuations in the local de
 nsity of states [3\,4] in our samples.\n\nReferenc
 es:\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. Savchenko\, D. A. Ritchie\, Phys. Rev. B 81\, 1
 93303 (2010).\n
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Departm
 ent of Physics
CONTACT:afw24
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