Kondo Screening Effect and Ferromagnetic Order in UCu₂Si₂

Abstract

Electrical resistivity and low temperature magnetoresistivity measurements made on a single crystal of UCu2Si2 are reported. By using as a phonon reference the temperature dependence of the electrical resistivity of ThCu2Si2 we could establish that UCu2Si2 has both a ferromagnetic and a Kondo behaviour. Such a phenomenon can be described by the underscreened Kondo lattice model. The magnetoresistivity revealed the presence of magnetic uctuations within the ferromagnetic order as it was reported previously for UGe2. Also one of the calculated Fermi surface sheets exhibits nesting properties, being in perfect agreement with the previous neutron diraction data, supporting the possibility of a presence of the spin density wave phase. In this ternary silicide, where the strong ferromagnetic behaviour exists, this phase is signalised by magnetic uctuations.