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SUMMARY:Determining the energy relaxation length scale in two-dimensional 
 electron gases (SP Workshop) - Mr Jordan Billiald\, University of Cambridg
 e\, Semiconductor Physics Group
DTSTART:20151125T141500Z
DTEND:20151125T151500Z
UID:TALK60989@talks.cam.ac.uk
CONTACT:Teri Bartlett
DESCRIPTION:I will present recent measurements of the energy relaxation le
 ngth scale in two-dimensional electron gases (2DEGS) [1]. To accomplish th
 is a bar-gate thermometer (BGT) was used to measure the local electron tem
 perature. A BGT is formed by over a symmetric pair of differentially biase
 d bar gates\, over which\, a thermovoltage develops in response to an elev
 ated electron temperature at its centre. Due to the mesoscopic size of the
  bar-gates\, the analysis of this thermovoltage requires a detailed model 
 including the energy relaxation length scale\, the elastic and inelastic p
 ower-law exponents for scattering events in the 2DEG\, and the geometry of
  the BGT itself. We develop this model along the lines of Rojek et al. [2]
 . The result is a good estimate of the local electron temperature\, and a 
 measure of the thermal relaxation length scale in the 2DEG itself. Confide
 nce in these results derives from ensuring they are consistent across data
  sets where the input power and also the electron density in the 2DEG are 
 varied. This work demonstrates a versatile low-temperature thermometry sch
 eme. I will also present our plans to use this thermometry technique to me
 asure the thermal conductivity of mesoscopic 2DEGs themselves\, as well as
  discuss possible future work to expand on what has already been done.\n\n
 [1] J. Billiald et al\, Appl. Phys. Lett. 107\, 022104 (2015)\; http://dx.
 doi.org/10.1063/1.4926338\n[2] S. Rojek and J. König\, Phys. Rev. B 90\, 
 115403 (2014).\n
LOCATION:Mott Seminar Room (Mott Building Room 531)\, Cavendish Laboratory
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