caa a22 4500 445381906 CHVBK 20180317143020.0 cr unu---uuuuu 170323e20110101xx s 000 0 eng 10.1007/s10948-010-1052-x doi (NATIONALLICENCE)springer-10.1007/s10948-010-1052-x Wachter P. Laboratorium für Festkörperphysik, ETH Zürich, 8093, Zürich, Switzerland aut Cu, Pu and Fe High T c Superconductors: All the Same Mechanism [Elektronische Daten] [P. Wachter] The more than 20 years old Cu high-T c superconductors exhibit as undoped parent materials antiferromagnetism. Upon doping the long-range antiferromagnetism disappears and only short-range antiferromagnetic clusters remain which show a spin pseudo-gap. There are no good ideas why long-range antiferromagnetism disappears upon the appearance of superconductivity because antiferromagnetism and superconductivity are compatible. A breakthrough has come about with the discovery of a plutonium (Pu) containing alloy PuCoGa5 with a T c of 18.5K. In principle not very exciting, but in the field of actinides T c's are not more than 3K because of the high mass and corresponding low phonon energies. The compound is a high-T c material in the field of actinides. But also this Pu-containing compound is a short-range antiferromagnet with a spin pseudo-gap. Apattern starts to develop! As well in the Cu as in the Pu compounds, some magnetic ions Cu2+ and Pu3+ are replaced upon doping with nonmagnetic Cu3+ or spontaneously with nonmagnetic Pu2+ ions, thus a mixed valence configuration appears with nonmagnetic states (spin holes) in antiferromagnetic clusters. The newly discovered Fe pnictide superconductors, however, have only one valence, Fe2+ above and below T N, the Néel temperature of 150K, as well above and below T c, as judged by the isomer shift of the Mössbauer effect. However, doping with fluorine, replacing oxygen, not only introduces electrons, but changes locally the crystal field acting on the iron ions. Divalent iron 3d6 has a high-spin configuration $\mathrm{t}_{2}^{4}\mathrm{e}^{2}$ in a magnetic Γ5 configuration and a nonmagnetic low-spin configuration $\mathrm{t}_{2}^{6}$ in a Γ1 state. So with the same valence we can have a magnetic and a nonmagnetic configuration, triggered by variation of the local crystal field induced by doping, causing again spin holes. We show that these spin holes in antiferromagnetic clusters have an attractive interaction and combine to make nonmagnetic bipolarons, which can condense and lead to superconductivity. Springer Science+Business Media, LLC, 2010 High T c superconductors nationallicence Magnetism nationallicence Models nationallicence Journal of Superconductivity and Novel Magnetism Springer US; http://www.springer-ny.com 24/1-2(2011-01-01), 127-135 1557-1939 24:1-2<127 2011 24 10948 https://doi.org/10.1007/s10948-010-1052-x text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10948-010-1052-x text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Wachter P. Laboratorium für Festkörperphysik, ETH Zürich, 8093, Zürich, Switzerland aut NATIONALLICENCE 773 0- Journal of Superconductivity and Novel Magnetism Springer US; http://www.springer-ny.com 24/1-2(2011-01-01), 127-135 1557-1939 24:1-2<127 2011 24 10948 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer