Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 78: Correlated Electrons: Poster Session
TT 78.58: Poster
Donnerstag, 10. März 2016, 15:00–18:30, Poster D
Scaling of the Optical Conductivity in the Transition from Thermal to Many-Body Localized Phases — •Robin Steinigeweg1, Jacek Herbrych2, Frank Pollmann3, and Wolfram Brenig4 — 1University of Osnabrück — 2CCQCN and University of Crete — 3MPIPKS Dresden — 4Technical University Braunschweig
We study the frequency dependence of the optical conductivity Re σ(ω) of the Heisenberg spin-1/2 chain in the transition from thermal to many-body localized phases induced by the strength of a spatially random magnetic field. Using the method of dynamical quantum typicality, we calculate the real-time dynamics of the spin-current autocorrelation function and obtain the Fourier transform Re σ(ω) in high frequency resolution and for system sizes L much larger than L ∼ 14 accessible to standard exact-diagonalization approaches. We unveil that the low-frequency behavior of Re σ(ω) is well described by Re σ(ω) ≈ σdc + a |ω|α, with α ≈ 1 in a wide range of the thermal phase and up to the many-body localized phase. We particularly detail the decrease of σdc as a function of increasing disorder for strong exchange anisotropies. We further find that the temperature dependence of σdc is consistent with the existence of a mobility edge.