Hyperfine Couplings and Delocalization

Visiting student Paulo Menegasso from Campinas State University in Brazil (now Dr. Menegasso) recently published his work on NMR in Ce(Rh,Ir)In₅. This work examined how the Knight shift of the In sites in this material evolves with Ir doping, as the Ce 4f electrons become more hybridized and the shape of the 4f wavefunction changes. Paulo found that the magnetic hyperfine coupling between the 4f electron spin and the In nuclear spin changed, reflecting an increase in the degree of itineracy of the 4f electrons. This work has important implications for understanding how heavy fermion materials behave near a quantum critical point.