Heat Capacity Measurement of Heavy Fermion YbCo2Zn20 under Magnetic Field

We have measured the specific heat of heavy fermion YbCo2Zn20 down to 0.1 K under magnetic field up to 3 T. At zero-field, the electronic contribution to the specific heat Ce/T shows logarithmic increase with decreasing temperature and tends to saturate at lower temperature, reflecting the Fermi-liquid state. With increasing magnetic field, Ce/T exhibits a power-law divergence at Hm ~ 0.6 T, which corresponds to the critical field of the metamagnetic crossover. The field dependence of Ce/T shows the two peak structure and the local minimum point of this structure coincides with Hm as observed in prototypical metamagnetic compound CeRu2Si2. We will compare the characteristic energy scale relevant to the metamagnetic behavior of YbCo2Zn20 and CeRu2Si2.