Weak ferromagnetism in Fe1-xCoxSb2

Weak ferromagnetism in Fe1-xCoxSb2 is studied by magnetization and Mossbauer measurements. A small spontaneous magnetic moment of the order of similar to 10(-3)mu(B) appears along the b axis for 0.2 <= x <= 0.4. Based on a structural analysis, we argue against extrinsic sources of weak ferromagnetism. We discuss our results in the framework of the nearly magnetic electronic structure of the parent compound FeSb2.