Crystal field anisotropy in a new Ytterbium heavy fermion ferromagnet

The Yb and Ce Kondo compounds display complex magnetic and electronic behavior, from heavy fermion metals to Kondo insulators. Their properties are often the result of competing energy scales, such as crystal field effects, exchange interactions and strong electronic correlations. Here I will discuss a novel regime in the area of strong correlated electron systems, that of fragile magnetism in a low carrier Kondo system Yb3Ir4Ge13. What sets this compound apart from the known low carrier or Kondo isulators is that the underlying electronic properties are set by the non-magnetic analogue Lu3Ir4Ge13, which is itself a low carrier semi-metal. Yb3Ir4Ge13 is therefore the first experimental realisation of multi-site honeycomb model in the dilute Kondo carrier limit.