Crystal structure and magnetism of Gd2MgGe2

The title compound, Gd2MgGe2, crystallizes in a ternary variant of the tetr agonal U3Si2 structure type with unit cell parameters of a=7.291(1) and c=4 .2826(8) Angstrom, space group P4/mbm, Z=2. Temperature (4.3-300 K) and mag netic field (0-50 kOe) dependencies of the dc magnetization, along with tem perature dependence of the ac magnetic susceptibility (25 Oe, 125 Hz) of Gd 2MgGe2 are presented. The behavior of both the dc magnetization and ac magn etic susceptibility above ca. 150 K indicates a disordered magnetic state f or Gd atoms while below ca. 150 K, it shows the existence of antiferromagne tic order. Tight-binding electronic structure (TB-LMTO-ASA) calculations in cluding spin-polarization are utilized to discuss the chemical bonding and provide insights for the magnetic ordering process in this compound. (C) 20 01 Elsevier Science B.V. All rights reserved.