Ferdinand Evers, University of Regensburg
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Abstract: The talk offers an overview on three related recent developments in mesoscopic physics. (i) The first part of the talk will review recent development in understanding the relaxation of charge and spin in interacting quantum wires (1d). As has recently been discovered, isotropic spin-chains, such as the Heisenberg chain, exhibit a high-temperature phase with critical dynamics, exponents and scaling functions situated in the universality class of the KPZ-model, which is completely classical. A brief account of the effect of interactions will be given leading to the physics of many-body localization. (ii) Numerical investigations of disordered electron films (2d) have revealed a very strong tendency in the local current density towards forming ring currents even in the absence of interactions. The phenomenon can be followed all the way down to the atomistic or molecular scale. As it turns out, the ring current density can exceed the transport currents by orders of magnitude. (iii) In equilibrium, ring currents are also known as persistent currents. We will demonstrate that their proper thermodynamic treatment requires to introduce a novel topological term in the definition of the entropy current density. The possible consequences will be discussed.