DYNAMICS OF 1ST-ORDER MAGNETIC PHASE-TRANSITION - RELAXATION PHENOMENA OF METAMAGNETISM IN FETIO3

Dynamical properties of metamagnetic transition in FeTiO3 have been investigated by monitoring the time-dependent change in magnetization of the spherical single crystal. The time evolution of the magnetization at the transition was found to be extremely slow; the relaxation time at 4.2 K reaches more than 15 min when the external field was suddenly increased from 70 kOe (< H(c) almost-equal-to 80 kOe) to 82.3 kOe (> H(c)). Systematic difference in the time dependence has been found in the antiferromagnetic to ferromagnetic (increasing field) and ferromagnetic to antiferromagnetic transition (decreasing field). Forced magnetostriction has also been measured at 4.2 K; a discontinuous change in length along the hexagonal c-axis at the metamagnetic transitions amounts to 0.01%, to which the slow relaxation of the magnetization may be ascribed.