Biomedical subjects

Thomas Nattermann

Publications and source records attributed to Thomas Nattermann.

4 recordsLinked to original sources

PubMed2006

Coulomb blockade and transport in a chain of one-dimensional quantum dots.

A long one-dimensional wire with a finite density of strong random impurities is modeled as a chain of weakly coupled quantum dots. At low temperature T and applied voltage V its resistance is limited by breaks: randomly occurring clusters of quantum dots with a special length distribution pattern that inhibit the transport. Because of the interplay of interaction and disorder effects the resistance can exhibit T and V dependences that can be approximated by power laws. The corresponding two exponents differ greatly from each other and depend not only on the intrinsic electronic parameters but also on the impurity distribution statistics.

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PubMed2004

Displacement profile of charge density waves and domain walls at critical depinning.

The influence of a strong surface potential on the critical depinning of an elastic system driven in a random medium is considered. If the surface potential prevents depinning completely the curvature C of the displacement profile exhibits at zero temperature a pronounced rhombic hysteresis curve of width 2f(c) with the bulk depinning threshold f(c). The hysteresis disappears at nonzero temperatures if the driving force is changed adiabatically. If the surface depins by the applied force or thermal creep, C is reduced with increasing velocity. The results apply, e.g., to driven magnetic domain walls, fluxline lattices, and charge-density waves.

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PubMed2003

Variable-range hopping and quantum creep in one dimension.

We study the quantum nonlinear response to an applied electric field E of a one-dimensional pinned charge-density wave or Luttinger liquid in the presence of disorder. From an explicit construction of low-lying metastable states and of bounce instanton solutions between them, we demonstrate quantum creep v=e(-c/E(1/2)) as well as a sharp crossover at E=E(*) towards a linear response form consistent with variable-range hopping arguments, but dependent only on electronic degrees of freedom.

Journal Article↗

PubMed2002

One-dimensional disordered density waves and superfluids: the role of quantum phase slips and thermal fluctuations.

The low temperature phase diagram of 1D disordered quantum systems such as charge or spin density waves, superfluids, and related systems is considered by a full finite- T renormalization group approach for the first time. At zero temperature the consideration of quantum phase slips leads to a new scenario for the unpinning (delocalization) transition. In the strong pinning limit the model is solved exactly. At finite T a rich crossover diagram with various scaling regions is found which reflects the zero temperature quantum critical behavior.

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