Magnetic phase diagram of the intermetallic compounds Gd1-xLaxMn2Ge2 and the effect of a field on transitions of the Mn subsystem from the antiferromagnetic into the ferromagnetic state

The magnetic properties of the intermetallic compounds Gd1 - xLaxMn2Ge2 (layered tetragonal crystal structure of the type ThCr2Si2), investigated in the present work and in [1] A. Sokolov, et al., Sol. State Commun. 105, 289 (1998), are discussed. It is shown that the basic characteristics of the magnetic ordering of these compounds-magnetic phase transitions from the ferrimagnetic into the antiferromagnetic state and vice versa-observed with increasing temperature in compositions with x < 0.1, the effect of a magnetic field on these transitions, the temperature dependences of the magnetization of these intermetallic compounds, as well as their magnetic T-x diagram can be described quantitatively in the Yafet-Kittel model for ferrimagnets with a negative exchange interaction in one of the sublattices using parameters determined in [2] A. Yu. Sokolov et al., JETP 89, 723 (1999) from investigations of the system Gd1 - xYxMn2Ge2, taking into account the dependence of the interplanar exchange interaction Mn-Mn on the crystal lattice parameter a. (C) 2000 MAIK "Nauka / Interperiodica".