Weak ferromagnetism of (Fe1-xNix)Si with B20 structure

Magnetic and electrical properties of Ni doped (Fe1-xNix)Si (x=0-0.5) have been studied by measuring magnetization, magnetic susceptibility and electrical resistivity. FeSi compound (x = 0) shows a weak ferromagnetic property at 2.0 K with small magnetization about 0.07 μB/f.u. at 50 kOe; high temperature magnetic susceptibility suggests paramagnetic property. By the substitution of Fe by Ni, low temperature weak ferromagnetic state is suppressed; magnetization continuously decreases with increasing x up to 0.5. Magnetic susceptibility shows Curie type temperature variation at low temperature; paramagnetic susceptibility does not obey the Curie-Weiss law for all samples. The electrical resistivity of (Fe1-xNix)Si indicates a semiconductive property at x = 0. The low temperature resistivity is substantially suppressed with increasing x; semimetallic and metallic property appears at x = 0.2 and 0.4, respectively.