Evolution from a magnetically correlated state to a single impurity state in heavy fermion system Ce 3− x La x Co 4 Sn 13

Ce 3 Co 4 Sn 13 crystallizes in the cubic Yb 3 Rh 4 Sn 13 structure, which is closely related to the one of scutterudites, well known thermoelectric materials. Ce 3 Co 4 Sn 13 exhibits novel physical properties, a large increase in C mag / T was recently observed at low temperatures with a maximum value of about 4 J K −2   ${\rm mol}_{{\rm Ce}}^{- 1} $ . The specific heat data suggested that Ce 3 Co 4 Sn 13 is likely near a magnetic quantum critical point (QCP). In this report we investigate the low‐temperature specific heat of Ce 3− x La x Co 4 Sn 13 in order to study the proximity of Ce 3 Co 4 Sn 13 to the possible magnetic QCP. We found the critical concentration x c  ≈ 0.6 which separates the magnetically correlated state with a maximum in C ( T )/ T at ∼0.7 K for x  <  x c , and a single impurity state for x  >  x c in heavy fermion (HF) system Ce 3− x La x Co 4 Sn 13 . However, for x c the low‐temperature C ( T )/ T behaviour is not characteristic of the QCP.