@article{BillHizhnyakovNevedrovetal., author = {Bill, Andreas and Hizhnyakov, Vladimir and Nevedrov, D. and Seibold, G{\"o}tz and Sigmund, Ernst}, title = {Electronic inhomogeneities, electron-lattice and pairinginteractions in high-Tc superconductors}, language = {en} } @article{SigmundHizhnyakovSeibold, author = {Sigmund, Ernst and Hizhnyakov, Vladimir and Seibold, G{\"o}tz}, title = {Electronic Phase Separation in High-Tc Superconductors}, language = {en} } @article{SeiboldSigmundHizhnyakov, author = {Seibold, G{\"o}tz and Sigmund, Ernst and Hizhnyakov, Vladimir}, title = {Spin-cluster states in CuO2 planes}, series = {Physical review B}, volume = {48}, journal = {Physical review B}, number = {10}, issn = {0556-2805}, pages = {7537 -- 7544}, language = {en} } @misc{BillHizhnyakovKremeretal., author = {Bill, Andreas and Hizhnyakov, Vladimir and Kremer, Reinhard K. and Seibold, G{\"o}tz and Shelkan, Aleksander and Sherman, Aleksei}, title = {Phase Separation and Pairing Fluctuations in Oxide Materials}, series = {Condensed Matter}, volume = {5}, journal = {Condensed Matter}, number = {4}, issn = {2410-3896}, doi = {10.3390/condmat5040065}, pages = {23}, abstract = {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.}, language = {en} } @misc{HizhnyakovSeibold, author = {Hizhnyakov, Vladimir and Seibold, G{\"o}tz}, title = {Nanoscale phase separation in cuprate superconductors}, series = {Physica C: Superconductivity and its Applications}, volume = {612}, journal = {Physica C: Superconductivity and its Applications}, issn = {1873-2143}, doi = {10.1016/j.physc.2023.1354309}, pages = {1 -- 7}, abstract = {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 M{\"u}ller. 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.}, language = {en} } @article{SigmundHizhnyakovSeibold, author = {Sigmund, Ernst and Hizhnyakov, Vladimir and Seibold, G{\"o}tz}, title = {Phase-Separation in High-Tc Superconductors}, series = {Physica C : Superconductivity}, volume = {Vol. 235-240}, journal = {Physica C : Superconductivity}, number = {1}, issn = {0921-4534}, pages = {253 -- 256}, language = {en} } @incollection{BillHizhnyakovSeibold, author = {Bill, Andreas and Hizhnyakov, Vladimir and Seibold, G{\"o}tz}, title = {Electronic Phase Separation and Electron-Phonon Coupling in Cuprate Superconductors}, series = {High-Tc Copper Oxide Superconductors and Related Novel Materials}, booktitle = {High-Tc Copper Oxide Superconductors and Related Novel Materials}, editor = {Bussmann-Holder, Annette and Keller, Hugo and Bianconi, Antonio}, publisher = {Springer International Publishing}, address = {Cham}, isbn = {978-3-319-52674-4}, doi = {10.1007/978-3-319-52675-1_1}, pages = {1 -- 14}, abstract = {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.}, language = {en} } @inproceedings{ShelkanSigmundHizhnyakovetal., author = {Shelkan, Aleksander and Sigmund, Ernst and Hizhnyakov, Vladimir and Seibold, G{\"o}tz}, title = {Free and spin-polaron states in high-Tc superconductor}, series = {Proceedings of the NATO Advanced Research Workshop on Colossal Magnetoresistance and Vibronic Interactions and the XVth International Jahn-Teller Symposium on Vibronic Interactions in Crystals and Molecules, Boston, August 16 - 22, 2000}, booktitle = {Proceedings of the NATO Advanced Research Workshop on Colossal Magnetoresistance and Vibronic Interactions and the XVth International Jahn-Teller Symposium on Vibronic Interactions in Crystals and Molecules, Boston, August 16 - 22, 2000}, editor = {Kaplan, Michael D.}, publisher = {Kluwer}, address = {Dordrecht [u.a.]}, isbn = {1-402-00044-8}, pages = {349 -- 356}, language = {en} } @article{SeiboldLetzSigmundetal., author = {Seibold, G{\"o}tz and Letz, M. and Sigmund, Ernst and Hizhnyakov, Vladimir}, title = {Mean-Field Theories of Spin-Cluster States in copper oxide planes}, language = {en} } @article{SeiboldSigmundHizhnyakov, author = {Seibold, G{\"o}tz and Sigmund, Ernst and Hizhnyakov, Vladimir}, title = {Spin-Polaron Formation and Phase Separation}, language = {en} } @article{SeiboldSigmundHizhnyakov, author = {Seibold, G{\"o}tz and Sigmund, Ernst and Hizhnyakov, Vladimir}, title = {Unrestricted slave-boson mean-field approximation for the two-dimensional Hubbard model}, series = {Physical review}, volume = {57}, journal = {Physical review}, number = {12}, issn = {0556-2805}, pages = {6937 -- 6942}, language = {en} } @incollection{HizhnyakovSigmundSeibold, author = {Hizhnyakov, Vladimir and Sigmund, Ernst and Seibold, G{\"o}tz}, title = {Polaron Formation and Percolative Phase Separation}, series = {Phase Separation in Cuprate Superconductors}, booktitle = {Phase Separation in Cuprate Superconductors}, publisher = {Springer}, address = {Berlin [u.a.]}, isbn = {3-540-57681-9}, pages = {50 -- 65}, language = {en} } @inproceedings{SigmundHizhnyakovSeibold, author = {Sigmund, Ernst and Hizhnyakov, Vladimir and Seibold, G{\"o}tz}, title = {Percolative Phase Separation and High-Tc superconductivity}, series = {Proceedings of the Workshop on Phase Separation in Cuprate Semiconductors, Erice, Italy, 1992}, booktitle = {Proceedings of the Workshop on Phase Separation in Cuprate Semiconductors, Erice, Italy, 1992}, publisher = {World Scientific}, address = {Singapore [u.a.]}, isbn = {981-02-1274-7}, pages = {46 -- 66}, language = {en} } @incollection{BillHizhnyakovSeiboldetal., author = {Bill, Andreas and Hizhnyakov, Vladimir and Seibold, G{\"o}tz and Sigmund, Ernst}, title = {Electronic Inhomogeneities and Pairing from Unscreened Interactions in High-Tc Superconductors}, series = {High-Tc Superconductors and Related Transition Metal Oxides}, booktitle = {High-Tc Superconductors and Related Transition Metal Oxides}, editor = {Bussmann-Holder, Annette}, publisher = {Springer}, address = {Berlin [u.a.]}, isbn = {978-3-540-71022-6}, pages = {143 -- 156}, language = {en} }