Competing magnetic interactions in the graphite-intercalation compound Li0.25Eu1.95C6

We present an extensive study of the magnetic properties of the new intercalation compound Li0.25Eu1.95C6 performed by dc magnetization, ac susceptibility, muon-spin and Mössbauer spectroscopy measurements as a function of temperature. The experimental results indicate that the magnetic behaviour of this compound is determined by the competition between magnetic inter- and intra-cluster correlations. The former are mainly due to ferromagnetic-like exchange interactions between Eu spins located between two graphene planes (at high temperature) or surrounding them (at low temperature). The latter correlations, instead, seem to arise from low-temperature antiferromagnetic-like exchange interactions between small magnetic intercalated domains (SMIDs).