NMR Studies of Yb-Based Heavy Fermion Compound YbCo2Zn20

We have carried out 59 Co-nuclear magnetic resonance (NMR) measurements on the heavy Fermion compound YbCo 2 Zn 20 , which shows an extremely large specific heat. After examining site symmetry at the Co position by studying a single crystal sample at different directions of magnetic field, we have analyzed powder patterns obtained over a wide range of field from 0.8 to 7.2 T. The temperature dependent component of the Knight shift, which arises from 4 f moments, is largely suppressed with increasing field, resulting in weak temperature dependence at low temperatures. This is a sign of field-induced Fermi liquid states, consistent with previous transport measurements on this compound.