Universal scaling behavior under pressure in the heavy-fermion antiferromagnet CeRh₂Si₂: Si 29 NMR study

The microscopic origin of a magnetic phase diagram under pressure in the heavy-fermion antiferromagnet CeRh2Si2 was investigated using the Si29 nuclear magnetic resonance (NMR) technique. Owing to the characteristics of the hyperfine form factor at the Si site, which filters specific q-dependent fluctuations around antiferromagnetic q vectors, we investigated the temperature and pressure dependences of q-independent local fluctuations caused by the single-site Kondo effect. A universal scaling behavior observed on the energy scale of the local fluctuations in the entire pressure region demonstrates that the characteristic energy scale T0 of Kondo interactions monotonically increases by applying pressure without a critical anomaly around the quantum critical pressure Pc of antiferromagnetism. Our NMR result agrees with the Doniach picture of the heavy-fermion phase diagram, where the progressive delocalization of the f electrons occurs across Pc, accompanied by the development of antiferromagnetic correlations among the f electrons.