Magnetic ordering of GdMn2

GdMn2 is a geometrically frustrated antiferromagnet that orders below T-N = 105 K, through a first-order transition with a large magnetovolume effect (Delta V/V approximate to 1%). Elastic neutron scattering measurements were performed on powder and single-crystal samples using short-wavelength beam (lambda = 0.5 Angstrom). No magnetic contribution to the nuclear peaks was found excluding any K = [0 0 0] component. Antiferromagnetic peaks were ob served, indexed with a propagation vector [2/3 2/3 0] and fitted with a non -collinear magnetic arrangement of both Mn and Gd sublattices. (C) 2000 Els evier Science B.V. All rights reserved.