The evolution of magnetic order in CrFe alloys. I. Antiferromagnetic alloys close to the critical concentration

Abstract

The dynamic magnetic response of an antiferromagnetic Cr-10 at.%Fe alloy was determined by neutron time-of-flight spectroscopy over the temperature range 10-250K. Quasielastic magnetic scattering was observed both above and below the Neel temperature at small scattering vectors ( kappa approximately 0.4 AA^-1). This scattering was attributed to the relaxation of ferromagnetically coupled clusters of Fe moments 5-10 AA in size which coexist with the antiferromagnetic spin density wave. The low-field magnetisation of several antiferromagnetic CrFe alloys was measured over the concentration range 10-15.5 at.%Fe and showed anomalies consistent with the freezing of such clusters at low temperatures.