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SUMMARY:Hierarchy of modes in an interacting system - Oleksandr Tsyplyatye
 v\, University of Birmingham
DTSTART:20141029T141500Z
DTEND:20141029T151500Z
UID:TALK55897@talks.cam.ac.uk
CONTACT:Teri Bartlett
DESCRIPTION:Studying interacting fermions in 1D at high energy\, we find a
   hierarchy in the spectral weights of the excitations theoretically and w
 e observe evidence for second-level excitations experimentally. Diagonalis
 ing a model of fermions (without spin)\, we show that levels of the hierar
 chy are separated by powers of R^2/L^2\, where R is a length-scale related
  to interactions and L is the system length. The\nfirst-level (strongest) 
 excitations form a mode with parabolic dispersion\, like that of a renorma
 lised single particle. The second-level excitations produce a singular pow
 er-law line shape to the first-level mode and multiple power-laws at the s
 pectral edge. We\nmeasure momentum-resolved tunnelling of electrons (fermi
 ons with spin) from/to a wire formed within a GaAs heterostructure\, which
  shows parabolic dispersion of the first-level mode and well-resolved\nspi
 n-charge separation at low energy with appreciable interaction strength. W
 e find structure resembling the second-level excitations\, which dies away
  quite rapidly at high momentum.\n
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Department of Physics
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