Spin dynamics in YbRh2Si2 probed by ESR

Recent electron spin resonance (ESR) experiments in the heavy-fermion metal YbRh2Si2 are discussed. A new approach is proposed for explanation of the first observation of ESR of a Kondo ion in a dense Kondo lattice system. Exchange interactions between the subsystems of the localized Yb3+ magnetic moments and itinerant electrons have been analyzed under conditions of their collective motion. Expressions for the effective ESR linewidth and g-factor with regard to the electron bottleneck and Kondo effect are obtained. The theoretical fits explain the experimental ESR data quite well. © 2005 Elsevier B.V. All rights reserved