Carrier relaxation dynamics in heavy fermion compounds
  The first femtosecond carrier relaxation dynamics studies in heavy fermion compounds are presented. The carrier relaxation time shows a dramatic hundred-fold increase below the Kondo temperature revealing a dramatic sensitivity to the electronic density of states near the Fermi level. 
J. Demsar, L.A. Tracy, R.D. Averitt, S.A.Trugman, J.L.Sarrao, A.J.   Taylor