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A theory of the scaling behavior of the thermodynamic, transport and dynamical properties of a three-dimensional metal at an antiferromagnetic (AFM) critical point is presented. It is show how the critical spin fluctuations at the AFM wavevector q = Q induce energy fluctuations at small q, giving rise to a diverging quasiparticle effective mass over the whole Fermi surface. The coupling of the fermionic and bosonic degrees of freedom leads to a self-consistent relation for the effective mass, which has a strong coupling solution in addition to the well-known weak-coupling spin-density wave solution. We thereby use the recently introduced concept of critical quasiparticles, employing a scale dependent effective mass ratio m*/m and quasiparticle weight factor Z. We specifically assume a scale dependent vertex correction boosting the coupling of fermions and spin fluctuations. The ensuing spin fluctuation spectrum obeys E/T-scaling. Our results are in good agreement with experimental data on the heavy fermion compounds YbRh2Si2 and CeCu6-xAux assuming 3D and 2D spin fluctuations, respectively.

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Peter Wölfle, KIT
Seminarraum Theoretische Physik
Contact: not specified