Magnetic phase transitions and phase diagrams of DyMn2Ge2

The experimental studies of magnetic phase transitions in the layered tetra gonal intermetallic compound DyMn2Ge2 are continued. The existence of spont aneous phase transitions is confirmed by the results of measurements of the temperature dependences of lattice parameters and the initial magnetic sus ceptibility. The measurements in strong (up to 50 T) and ultrastrong (up to 150 T) fields revealed two new field-induced magnetic transitions. The inc lusion of the exchange interaction between next-to-nearest layers of mangan ese and the crystal field effects for the rare-earth subsystem along with t he antiferromagnetic exchange interaction of nearest Mn layers has made it possible to describe the magnetic properties of DyMn2Ge2 in a wide range of magnetic fields. The parameters of these interactions are determined from a comparison of the experimental and theoretical magnetization curves and H -T phase diagrams. (C) 2001 MAIK "Nauka/Interperiodica".