Inhomogeneous magnetism in the CeNi/Cu pseudobinary compounds

Muon spin relaxation measurements have been performed over the wide temperature range from 0.4 to 200 K in some representative CeNi1-xCux compositions (0.2⩽x⩽0.6) where a cluster-glass phase at temperatures above the ferromagnetic ground state has been characterized by AC-DC magnetization measurements. The analysis of these data reveals the presence of a highly inhomogeneous magnetic state at temperatures above the freezing temperature Tf (seen by AC susceptibility) that runs into the paramagnetic regime. This inhomogeneous magnetic state consists of long-range ordered and non-ordered fractions, the latter increasing with temperature. An unusual strong dependence of the μSR magnetic response on magnetic field history such as zero field cooling vs. field cooling within the intermediate magnetically inhomogeneous range is found. The present analysis considering also previous neutron scattering, magnetic characterization, specific heat allows us to present a complete description of the system. We propose that the long-range magnetic order at low temperature is achieved by a percolative process of magnetic clusters that become static below Tf.