NMR studies on heavy fermion and conventional metal superlattices CeCoIn₅/YbCoIn₅

We performed nuclear magnetic resonance (NMR) experiments on heavy fermion and conventional metal superlattices CeCoIn₅/YbCoIn₅. We succeeded in identifying the signals arising from CeCoIn₅ and YbCoIn₅ block layers (BLs) by comparing the spectra of the CeCoIn₅/YbCoIn₅ superlattices, CeCoIn₅ thin film, and YbCoIn₅ thin film. Furthermore, we found that the signals of Ce-BLs could be divided into signals arising from interfacial layers and inner layers even in one Ce-BL by comparing the spectra of two CeCoIn₅/YbCoIn₅ superlattices with different thickness of the Ce-BLs. A comparison of the spectra of the superlattices with different Ce-BL thickness and field dependence of nuclear-spin lattice relaxation rate 1/T₁ indicate that antiferromagnetic spin fluctuations at the interfacial site are more suppressed than those at the inner layer site even in the Ce-BLs.