Possible critical behavior and field-induced magnetic transition in YbCo$_2$

The first study of electrical resistivity, magnetization and specific heat on YbCo$_2$ is reported. The measurements on single-phased sample of YbCo$_2$ bring no-evidence of magnetic ordering down to 0.3 K in zero magnetic field. The manifestations of low Kondo temperature are observed. It can explain evidently the very large electronic specific heat which places YbCo$_2$ among heavy fermion systems. Application of magnetic field revealed metamagnetic-like anomaly and field induced transition-like behavior. Despite the metamagnetic-like anomaly being weakly pronounced, the temperature-dependent measurements show obvious field induced-like transition under magnetic field above 2 T. Further, ferromagnetic character is exhibited as the transition temperature increases with increasing field. The origin of the observed properties is discussed in comparison and contrast with other RCo$_2$ and Yb-based heavy fermion compounds. It indicates that in the unique case of YbCo$_2$, the itinerant electron magnetism of Co 3d-electrons and the Kondo effect within the vicinity of quantum criticality of Yb 4f-local moments can both play a role.