Concepedia

Abstract

The magnetization and transport properties have been studied in the intermetallic system TiFexCo1−x, where 0≤x≤1. The composition x=0.5 is superconducting while all other alloys within the composition range 0.3<x<0.7 are ferromagnetic. Below the ferromagnetic transition temperature, alloys with 0.5<x<0.7 exhibit conventional field dependences, saturating at 2 kOe with a moment of the order of 10 emu/gm. Alloys with 0.3<x<0.5 do not saturate in fields of less than 25 kOe. The magnetization of the alloy with x=0.5 is nearly linear in field and no Curie temperature is observed. The magnitude of the magnetization is lower than neighboring compositions by a factor of four. The composition range of this behavior is very narrow, as alloys with x=0.55 and x=0.45 are ferromagnetic. Compositions with x<0.3 and x>0.7 are not ferromagnetic but exhibit paramagnetism presumably due to conduction electrons. The residual electrical resistivity appears to follow Nordheim's rule, suggesting disordered alloys, including the x=0.5 composition. The alloy x=0.5 has a superconducting transition temperature of 3.3°K, all other compositions within 0.3<x<0.7 not being superconductors. The low-temperature ideal resistivity is found to vary as T2, but near the composition x=0.5 the temperature dependence differs from T2. This is taken to be a result of multiband deviations from Matthiessen's rule. The implication is that the superconductivity is associated with only a portion of the Fermi surface.