Temperature-induced magnetism in FeSi

Abstract

We report neutron-scattering measurements with polarization analysis on a large single crystal of FeSi up to 650 K. A strongly q-dependent magnetic scattering is observed around (011) and the intensity follows the unusual shape of the static susceptibility. Surprisingly, the energy-integrated magnetic cross sections are almost q independent. This represents an entirely new kind of magnetism which, overall, supports the picture of temperature-induced moment in FeSi.