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Open AccessFeature PaperArticle

Phase Separation and Pairing Fluctuations in Oxide Materials

1
Department of Physics & Astronomy, California State University Long Beach, Long Beach, CA 90840, USA
2
Institute of Physics, University of Tartu, 1 W. Ostwaldi Street, 50411 Tartu, Estonia
3
MPI for Solid State Research Heisenbergstraße 1, 70569 Stuttgart, Germany
4
Institut für Physik, BTU Cottbus, P.O. Box 101344, 03013 Cottbus, Germany
*
Author to whom correspondence should be addressed.
Condens. Matter 2020, 5(4), 65; https://doi.org/10.3390/condmat5040065
Received: 12 September 2020 / Revised: 6 October 2020 / Accepted: 13 October 2020 / Published: 19 October 2020
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. View Full-Text
Keywords: phase separation; cuprate superconductors; electronic correlations phase separation; cuprate superconductors; electronic correlations
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MDPI and ACS Style

Bill, A.; Hizhnyakov, V.; Kremer, R.K.; Seibold, G.; Shelkan, A.; Sherman, A. Phase Separation and Pairing Fluctuations in Oxide Materials. Condens. Matter 2020, 5, 65.

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