MULTISTEP METAMAGNETISM IN 4F AND 5F ELECTRON-SYSTEMS

We present recent results of high-field magnetization and neutron diffraction studies of Ising-like systems of PrCo2Si2, UPdIn and TbNi2Si2 using single crystal samples. PrCo2Si2 undergoes four-step metamagnetic transitions in the c-axis magnetization curve M(H) up to 30 T at 1.3 K, where an antiferromagnetic structure with k = (0, 0, 1) is realized in zero magnetic field. The c-axis M(H) curve at 4.2 K of TbNi2Si2 exhibits at least nine different magnetic structures which are characterized by different wave vectors k = (1/2 +/- tau, 1/2 -/+ tau, 0) with tau = 0.00, 0.075, 0.080, 0.090, 0.100, 0.125, 0.100 and 0.105 in the sequence of increasing magnetic field, being a typical example of the devil's staircase.