High-Field Magnetization Studies of Two-Dimensional Copper Antiferromagnets

Abstract

The magnetic susceptibilities and high-field magnetization data for members of two families of S = 1/2, two-dimensional, square antiferromagnetic lattices are reported. The known compounds bis-2-amino-5-methylpyridinium tetrabromocuprate, 1, and bis-2-amino-5-chloropy-ridinium tetrabromocuprate, 2, crystallize in the space group C2/c with the tetrabromocuprate ions related by the C-centering and unit cell translations, leading to a square magnetic lattice. Similarly bispyrazinecopper(II) perchlorate, 3, and bispyrazinenitratocopper(II) hex-afluoro-phosphate, 4, crystallize in the space groups C2/m and I4/mcm respectively and also generate square magnetic lattices. High-field magnetization studies, up to 60 Tesla, have determined their saturation fields to be 21 T (1), 27 T (2), 53 T (3) and 32 T (4). All show upward curvature in plots of magnetization as a function of field and fall on a universal curve in good agreement with recent theoretical predictions.