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DTSTAMP:20260404T110126Z
UID:1586872800@ist.ac.at
DTSTART:20200414T160000
DTEND:20200414T180000
DESCRIPTION:Speaker: Leonid Levitov\nhosted by Maksym Serbyn \nAbstract: It
  was found recently that 2D electron fluids can support collective excitat
 ions that are not subject to Landau's T^2 dissipation [1\,2\,3]. This surp
 rising behavior originates from the head-on carrier collisions\, a process
  that dominates angular relaxation at not-too-high temperatures T<<T_F due
  to the joint effect of Pauli blocking and kinematic constraints. As a res
 ult\, a large family of exceptionally long-lived excitations emerges\, ass
 ociated with the odd-parity harmonics of momentum distribution. This leads
  to "tomographic" dynamics: fast 1D spatial diffusion along the unchanging
  velocity direction accompanied by a slow angular dynamics that gradually 
 randomizes velocity orientation. The abnormally slow angular relaxation or
 iginates from correlated angular dynamics involving "lock-step'' angular d
 isplacements along the Fermi surface occurring in collinear two-particle c
 ollisions. The slow loss of directional memory is described as non-Brownia
 n angular random walk\, "superdiffusion" on the Fermi surface. The collect
 ive behavior with directional memory dominates at moderately long times\, 
 pushing the onset of conventional hydrodynamics to abnormally large timesc
 ales. The tomographic regime features an unusual hierarchy of time and len
 gth scales\, resulting in scale-dependent transport coefficients. The scal
 e dependence manifests itself in fractional-power current flow profiles an
 d unusual conductance scaling vs. temperature and sample size. This exotic
  behavior can be directly probed by transport measurement techniques\, as 
 well as by momentum-resolved tunneling measurements.1. P J Ledwith\, H Guo
 \, L Levitov\, The Hierarchy of Excitation Lifetimes in Two-Dimensional Fe
 rmi Gases\, Annals of Physics 411\, 167913 (2019)2. P J Ledwith\, H Guo\, 
 A V Shytov\, L Levitov\, Tomographic Dynamics and Scale-Dependent Viscosit
 y in Two-Dimensional Electron Systems\, Phys Rev Lett 123\, 116601 (2019)3
 . P J Ledwith\, H Guo\, L Levitov\, Angular Dynamics and Directional Memor
 y in Two-Dimensional Electron Fluids\, 2019
LOCATION:Webinar\, ISTA
ORGANIZER:
SUMMARY:Leonid Levitov: [Webinar] Long-Lived Excitations\, Directional Memo
 ry and Hydrodynamic Transport in Two-Dimensional Electron Fluids
URL:https://talks-calendar.ista.ac.at/events/2748
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