Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 45: Correlated Electrons: Poster Session

TT 45.9: Poster

Thursday, March 29, 2012, 15:00–19:00, Poster B

Theory of the Spin Exciton Formation inside the Hidden Order Phase of CeB₆ — •Alireza Akbari and Peter Thalmeier — Max Planck Institute for the Chemical Physics of Solids, D-01187 Dresden, Germany

The heavy fermion metal CeB ₆ exhibits hidden order of antiferroquadrupolar (AFQ) type below T_Q=3.2K and subsequent antiferromagnetic (AFM) order at T_N=2.3K. It was interpreted as ordering of the quadrupole and dipole moments of a Γ₈ quartet of localised Ce 4f¹ electrons. This established picture has been profoundly shaken by recent inelastic neutron scattering [1] that found the evolution of a feedback spin exciton resonance within the hidden order phase at the AFQ wave vector appears and is stabilized by the AFM order. We develop an alternative theory based on a fourfold degenerate Anderson lattice model, including both order parameters as particle-hole condensates of itinerant heavy quasiparticles. This explains in a natural way the appearance of the spin exciton resonance and the momentum dependence of its spectral weight, in particular around the AFQ vector and its rapid disappearance in the disordered phase. Analogies to the feedback effect in unconventional superconductors and Kondo semiconductors are pointed out.
G. Friemel et al., arXiv:1111.4151.