NONCOLLINEAR SPIN STRUCTURE IN ZN0.825CU0.175CR2SE4

We have measured the magnetization of two compounds in the Zn1-xCuxCr2 Se4 series. As the applied field is increased three transitions of sec ond order are observed. From the magnetization curves we obtain the cr itical fields for these transitions, the spontaneous magnetization for each spin structure as well as the high field susceptibility. It seem s that three transition fields separate four spin structures, namely, cone, alignment in the meridian plane, oscillation in this plane and p arallel alignment. From the experimental data we have calculated the a nisotropy energy, the anisotropy field, the anisotropy constant, the a nisotropy energy density as the magnetic energy difference between the two mutually perpendicular directions, the exchange constants and the Curie constants.