Complex magnetism in Fe2VSi

Magnetic susceptibility and 51V NMR measurements are reported for two samples of the Heusler alloy Fe2VSi: Both samples have been quenched, one after annealing at 1073 K (sample 1) and the other at 1123 K (sample 2). The susceptibilities of both samples have been found to depend strongly on the applied static magnetic field. A new magnetic transition is found at 300 K for sample 2. NMR line widths of 51V become appreciably broader at 80 K for sample 1 and at 150 K for sample 2. These temperatures do not correspond to the magnetic and crystallographic transition temperatures determined by diffraction experiments. The NMR widths are governed by the combined effects of the hyperfine fields from ferromagnetic iron clusters in the crystals and the intrinsic antiferromagnetic spin structures.