STATIC MAGNETIC-PROPERTIES OF THE MANY-SUBLATTICE ANTIFERROMAGNET CA2FE2O5

We have studied the magnetization of the antiferromagnet dicalcium fer rite Ca2Fe2O5 in magnetic fields up to 5.5 T and in the temperature ra nge 5-330 K. Temperature dependences of the weak ferromagnetic moment m0 and susceptibilities along the main crystallographic axes have been measured. Effective intrinsic parameters, such as an exchange field a nd the Dzyaloshinskiy-Moriya field have been obtained as a function of temperature. Possible magnetic structures have been analyzed by means of comprehensive group-theoretical consideration and a phenomenologic al free energy has been derived. Problems involving hedgehog structure , parallel susceptibility, field-induced spin reorientation, magnitude of the Dzyaloshinskiy-Moriya interaction, and the origin of the weak ferromagnetism are also discussed. It is shown that Ca2Fe2O5 can be de scribed as two canted antiferromagnets putting one into another with a n antiferromagnetic interaction between the weak ferromagnetic compone nts.