Magnetically induced transition from weakly into strongly anisotropic state in Tb-Y ferrite garnets

Magnetization and differential magnetic susceptibility of TbxY3-xFe5O12 (x<0.5) are studied in pulsed magnetic fields of up to 40T amplitude at T=4.2K. It is observed that remagnetization of a rare earth subsystem of such ferrite-garnets proceeds through one or several jumps of magnetic momentum depending on field orientation with respect crystallographic sample axes. The obtained results are interpreted assuming that a noncomplanar structure, formed by Ising magnetic momenta, occurs in the field. By extrapolation to x→0 a value of the effective field of exchange interaction between the rare earth and ''iron'' subsystems of terbium ferrite garnet is determined