Regensburg 2010 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 26: CE: Heavy Fermions
TT 26.14: Talk
Wednesday, March 24, 2010, 17:45–18:00, H21
Theory of spin exciton in the Ce-based unconventional superconductors — •Alireza Akbari1, Ilya Eremin1, Peter Thalmeier2, and Peter Fulde1 — 1Max Planck Institute for the Physcis of Complex Systems, D-01187 Dresden, Germany — 2Max Planck Institute for the Chemical Physics of Solids, D-01187 Dresden, Germany
The feedback spin resonance was observed in inelastic neutron scattering (INS) experiments for numerous unconventional superconductors. In particular a different kind of feedback has been found in the Ce-based ferropnictides. We analyze the influence of unconventional superconductivity on crystalline electric field (CEF) excitations of rare-earth ions. Our theoretical model shows that the resonant magnetic excitations of the conduction electrons below Tc is a result of the formation of the bound state in the 4f-electron susceptibility at energies well below the CEF excitation energy. The transition between CEF split Ce-4f states has anomalous shift and line-width which is explained as an effect of coupling to resonant 3d spin excitations below Tc giving evidence for a S± state.
[1] S. Chi et al Phys. Rev. Lett. 101, 217002 (2008).
[2] G. Yu, et al, arXiv:0803.3250 (unpublished).
[3] A. Akbari, I. Eremin, P. Thalmeier, and P. Fulde, Phys. Rev. B, 80, 100504R (2009).