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CATEGORIES:Semiconductor Physics
SUMMARY:Momentum effects on focusing in one-dimensional sy
 stems - Miss Kavitha Kishen (Semiconductor Physics
  Group\, Cavendish Laboratory)
DTSTART;TZID=Europe/London:20070129T141500
DTEND;TZID=Europe/London:20070129T151500
UID:TALK6539AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/6539
DESCRIPTION:The quantisation of conductance into units of 2e^2
 ^/h in a one-dimensional\nchannel is well understo
 od.  In a high dc bias\, additional features are\n
 observed at low conductances (G &lt\; 2e^2^/h)whic
 h have not\, as yet\,  been fully\nexplained.  Rec
 ently it has been suggested that the presence of a
  feature in\nthe region of 0.2-0.3(2e^2/^h) is due
  to polarisation of the 1D subbands by a\nhigh dc 
 bias.  Focusing measurements have been demonstrate
 d to allow 1D\nchannels to act as spin-filters. I 
 will review work in related fields and\nthen prese
 nt the first investigation into the effect of the 
 low conductance\ndc bias feature on focusing spect
 ra.  The device studied consists of an\nemitter an
 d collector of standard measurements with an addit
 ional gate\naffecting the 2DEG through which elect
 rons travel whilst focusing. There are\nseveral fe
 atures of interest in the data most importantly a 
 shift in\nfocusing peaks with emitter conductance 
 which is\ndirectly related to the presence of the 
 dc bias feature.  I will explain why\nwe attribute
  this to a change in electron momentum direction a
 nd discuss the\npossibilities for further work in 
 this area.\n
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Departm
 ent of Physics
CONTACT:K DAS GUPTA
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