Events

Department of Magnetic Reseach Seminar

Spin and charge dynamics in disordered chains

prof. dr hab. Marcin Mierzejewski

Katedra Fizyki Teoretycznej Politechniki Wrocławskiej

Experiments on many-body localization are performed on cold–fermion lattices where the relevant model is the Hubbard model with spin–1/2 fermions, where the disorder enters only via a random charge potential. Recent numerical studies of such model reveal that even at strong disorder, localization and nonergodicity occurs only in the charge subsystem [1,2], unless one introduces also random magnetic field [3]. We derive and study the effective spin model [4] that explains the anomalous spin dynamics in the one-dimensional Hubbard model with strong potential disorder.  Assuming that charges are localized, we show that spins are delocalized and their subdiffusive transport [1] originates from a singular random distribution of spin exchange interactions.  The exponent relevant for the subdiffusion is determined by the Anderson localization length and the density of electrons. While the analytical derivations are valid for low particle density, numerical results for the full Hubbard model reveal a qualitative agreement up to half-filling. The presentation will start with an overview of the Anderson and the many-body localization phenomena.

• [1] Prelovšek, O. S. Barišić,  M. Žnidarič, Phys. Rev. B 94, 241104 (2016).
• [2] Mierzejewski, M. Kozarzewski, P. Prelovšek, Phys. Rev. B 97, 064204 (2018).  
• [3] Lemut, M. Mierzejewski, J. Bonča, Phys. Rev. Lett. 119, 246601 (2017).
• [4] Kozarzewski, P. Prelovšek, M. Mierzejewski, arXiv:1803.09667.