Rudi Hackl

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Inelastic light scattering is an intensively used tool in the study of electronic properties of solids. Triggered by the discovery of high temperature superconductivity in the cuprates and by new developments in instrumentation, light scattering both in the visible (Raman effect) and the X-ray part of the electromagnetic spectrum has become a method(More)
We measure the anisotropic midinfrared response of electrons and phonons in bulk YBa(2)Cu(3)O(7-δ) after femtosecond photoexcitation. A line shape analysis of specific lattice modes reveals their transient occupation and coupling to the superconducting condensate. The apex oxygen vibration is strongly excited within 150 fs, demonstrating that the lattice(More)
The electron dynamics in the normal state of Bi(2)Sr(2)CaCu(2)O(8+delta) is studied by inelastic light scattering over a wide range of doping. A strong anisotropy of the electron relaxation is found which cannot be explained by single-particle properties alone. The results strongly indicate the presence of an unconventional quantum-critical metal-insulator(More)
The split personality of the conduction electrons in one high-temperature superconductor might indicate that periodic modulations of their spin and charge density are a general feature of these mystifying materials. In simple metals, conduction electrons undergo well-understood phase transitions: they can become superconducting or ferro-magnetic, or acquire(More)
In this article we consider the optimization of np-complete problems with a genetic algorithm. For " real word " problems we regard it to be sufficient to get close to the optimal solution without any guarantee of ever hitting it. Our algorithm was tested on two problem classes: the traveling salesman problem and the product ordering problem; the first is a(More)
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