Field-induced quantum criticality of systems with ferromagnetically coupled structural spin units

The field induced quantum criticality of compounds with ferromagnrtically coupled structural spin units ( as dimmers and ladders ) is explored by applying Wilson's renormalization group framework to an appropriate effective action. We determine the low temperature phase boundary and the behavior of relevant quantities decreasing the temperature with the applied magnetic field fixed at its quantum critical point value. In this context a plausible interpretation of some recent experimental results is suggested.