De Haas-Van Alphen oscillations in the diluted magnetic semiconductor mercury(1-x)iron(x)selenium

de Haas-van Alphen measurements are performed in oriented single crystals of Hg{dollar}sb{lcub}rm 1-x{rcub}{dollar}Fe{dollar}sb{lcub}rm x{rcub}{dollar}Se in the range 0.0 {dollar}leq{dollar} x {dollar}leq{dollar} 0.05 for 0.5 {dollar}<{dollar} T {dollar}<{dollar} 4.2K for the magnetic field range 0.2 T {dollar}<{dollar} H {dollar}<{dollar} 1.0 T. These data can be interpreted in terms of a closed orbit magnetic breakdown model. The effect of Fe on the conduction band is explored in some detail. It is found that the presence of Fe lowers the Dingle temperature in a non-monotonic fashion, i.e., there is a minimum in the Dingle temperature for x {dollar}sim{dollar} 0.001. This effect cannot be attributed to a gross modification of the band structure. Effective mass measurements are in good agreement with those expected for HgSe. However, the presence of Fe is seen to have a subtle effect on the band structure. The overall symmetry of the band structure may be modified by the addition of Fe. Furthermore, the presence of Fe tends to decrease the inversion asymmetry splitting of the conduction band as evidenced in the low-field beating.