Refine
Year of publication
Document Type
Way of publication
- Open Access (1)
Language
- English (14)
Keywords
- Ceramics (1)
- Composites (1)
- Cuprates (1)
- Electronic inhomogeneities (1)
- Glass (1)
- Nanochemistry (1)
- Natural Materials (1)
- Optical and Electronic Materials (1)
- Phase separation (1)
- Spectroscopy and Microscopy (1)
Institute
The microscopic mechanism of charge instabilities and the formation of inhomogeneous states in systems with strong electron correlations is investigated. We demonstrate that within a strong coupling expansion the single-band Hubbard model shows an instability towards phase separation and extend the approach also for an analysis of phase separation in the Hubbard-Kanamori hamiltonian as a prototypical multiband model. We study the pairing fluctuations on top of an inhomogeneous stripe state where superconducting correlations in the extended s-wave and d-wave channels correspond to (anti)bound states in the two-particle spectra. Whereas extended s-wave fluctuations are relevant on the scale of the local interaction parameter U, we find that d-wave fluctuations are pronounced in the energy range of the active subband which crosses the Fermi level. As a result, low energy spin and charge fluctuations can transfer the d-wave correlations from the bound states to the low energy quasiparticle bands. Our investigations therefore help to understand the coexistence of stripe correlations and d-wave superconductivity in cuprates.
Electronic inhomogeneities are nowadays a well established feature of high-temperature superconductors, most prominently exemplified by the observation of charge-ordered states in a large number of cuprate materials. In this contribution we review the particular contribution of the Stuttgart-Tartu-Cottbus group to this field, which has been largely stimulated by intense discussion with K. Alex Müller. The original scenario, which was based on the formation of a percolative electronic network, is substantiated by a microscopic analysis of the clustering of magnetic polarons within the one-band Hubbard model.
Nanoscale electronic inhomogeneities are nowadays a well established feature of high-temperature superconductors, most prominently exemplified by the observation of charge-ordered states in a large number of cuprate materials. These inhomogeneities have profound consequences for the electron–phonon coupling since they allow for long-range pairing interactions due to the reduced screening supplemented by the enhancement of the electron–phonon vertex due to strong correlations. In this chapter we review the particular contribution of the Stuttgart-Tartu-Cottbus group to this field and discuss how the current status of experimental results provides affirmation to their ideas.