de Haas-van Alphen Effect in Antiferromagnetic Cr-Rich Alloys

De Haas-van Alphen measurements have been made on Cr-rich alloys with up to 2-at.% V and 1-at.% Mn. In the crystals in which the antiferromagnetic wave vector $\overrightarrow{\mathrm{q}}$ is incommensurate with a reciprocal-lattice vector, the changes in three of the frequencies associated with hole ellipsoids at $N$ are consistent with changes in $\overrightarrow{\mathrm{q}}$, rather than with a geometrical change in the size of the hole ellipsoids upon alloying. In the crystal in which $\overrightarrow{\mathrm{q}}$ is commensurate with a reciprocal-lattice vector, several frequency branches were observed. The angular dependence of these branches is consistent with simple ellipsoid models of the Fermi surface.