2-STEP METAMAGNETIC PHASE-TRANSITION INDUCED BY A MAGNETIC-FIELD PARALLEL TO THE B-AXIS IN DYFEO3

By means of magnetic and magneto-optic studies performed in the temper ature range 1.7-6 K, the phase diagram of DyFeO3 in the presence of a magnetic field in the crystallographic (ab) plane was determined. Desp ite earlier theoretical predictions, a certain temperature interval wa s found in which the transition from the Gamma(5)(g(x)a(y))Gamma(1)(G( y)A(x)C(z)) to the Gamma(3)(f(y)c(x))Gamma(4)(G(x)A(y)F(z)) phase is a two-step transition even when the magnetic field is directed exactly along the b-axis. A qualitative explanation of the observed phenomena resulting from the appearance of the Gamma(1234)(F(x)F(y)F(z)G(x)G(y)G (z)) phase in the iron subsystem, is proposed.