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SUMMARY:Momentum effects on focusing in one-dimensional systems - Miss Kav
 itha Kishen (Semiconductor Physics Group\, Cavendish Laboratory)
DTSTART:20070129T141500Z
DTEND:20070129T151500Z
UID:TALK6539@talks.cam.ac.uk
CONTACT:K DAS GUPTA
DESCRIPTION:The quantisation of conductance into units of 2e^2^/h in a one
 -dimensional\nchannel is well understood.  In a high dc bias\, additional 
 features are\nobserved at low conductances (G &lt\; 2e^2^/h)which have not
 \, as yet\,  been fully\nexplained.  Recently it has been suggested that t
 he presence of a feature in\nthe region of 0.2-0.3(2e^2/^h) is due to pola
 risation of the 1D subbands by a\nhigh dc bias.  Focusing measurements hav
 e been demonstrated to allow 1D\nchannels to act as spin-filters. I will r
 eview work in related fields and\nthen present the first investigation int
 o the effect of the low conductance\ndc bias feature on focusing spectra. 
  The device studied consists of an\nemitter and collector of standard meas
 urements with an additional gate\naffecting the 2DEG through which electro
 ns travel whilst focusing. There are\nseveral features 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
  and discuss the\npossibilities for further work in this area.\n
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Department of Physics
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