Evolution of hyperfine parameters across a quantum critical point in CeRhIn5

We report nuclear magnetic resonance (NMR) data for both the In(1) and In(2) sites in the heavy-fermion material CeRhIn5 under hydrostatic pressure. The Knight shift data reveal a suppression of the hyperfine coupling to the In(1) site as a function of pressure, and the electric field gradient nu(alpha alpha) at the In(2) site exhibits a change of slope d nu(alpha alpha)/dP at P-c1 = 1.75 GPa. These changes to the coupling constants reflect alterations to the electronic structure at the quantum critical point.