Magnetically driven superconductivity in CeCu 2 Si 2

The origin of unconventional superconductivity, including high-temperature and heavy-fermion superconductivity, is still a matter of controversy. Spin excitations instead of phonons are thought to be responsible for the formation of Cooper pairs. Using inelastic neutron scattering, we present the fi...

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Bibliographic Details
Published in:Nature physics 2011-02, Vol.7 (2), p.119-124
Main Authors: Arndt, J, Steglich, F, Jeevan, H. S, Schmidt, W, Faulhaber, E, Schmalzl, K, Stockert, O, Loewenhaupt, M, Geibel, C, Kirchner, S, Si, Q
Format: Article
Language:English
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Summary:The origin of unconventional superconductivity, including high-temperature and heavy-fermion superconductivity, is still a matter of controversy. Spin excitations instead of phonons are thought to be responsible for the formation of Cooper pairs. Using inelastic neutron scattering, we present the first in-depth study of the magnetic excitation spectrum in momentum and energy space in the superconducting and the normal states of CeCu2Si2. A clear spin excitation gap is observed in the superconducting state. We determine a lowering of the magnetic exchange energy in the superconducting state, in an amount considerably larger than the superconducting condensation energy. Our findings identify the antiferromagnetic excitations as the main driving force for superconducting pairing in this prototypical heavy-fermion compound located near an antiferromagnetic quantum critical point.
ISSN:1745-2473
1745-2481
DOI:10.1038/nphys1852