T-dependent nuclear hyperfine coupling at the In site in CeIrIn

Kambe, Shinsaku  ; Sakai, Hironori   ; Tokunaga, Yo  ; Matsuda, Tatsuma; Haga, Yoshinori   ; Takeuchi, Tetsuya*; Onuki, Yoshichika*; Walstedt, R. E.*

We report an In NMR study of a single-crystal sample of the heavy fermion superconductor CeIrIn. The observed non-linear variation of Knight Shift with static susceptibility in the normal state is consistent with the two-fluid (components) model of Nakatsuji et al, indicating that two individual contributions to static susceptibility exist. However, our results can also be understood in terms of a T-dependent hyperfine coupling, which accounts for the spin-lattice relaxation data naturally on the basis of a one-component dynamical susceptibility. In addition, the observed T-dependence of the hyperfine coupling is scaled to a density of states given by dynamical mean field theory (DMFT). We believe that this contrast between the static and dynamical properties is a crucial dual nature of the heavy fermion crossover, which related with the coherence between localized and itinerant excitations.