X-band electron paramagnetic resonance of a quasi-bidimensional molecular composite [NH 3(CH 2) 4NH 3]CuCl 4

Abstract

Electron paramagnetic resonance (EPR) experiments on a single crystal of [NH 3(CH 2) 4NH 3]CuCl 4, with a quasi-bidimensional structure, have been carried out when rotated around a, b and c ∗ axes, at X-band. A careful analysis of experimental data permits one to obtain the principal values of the g-factors g ⊊ = 2.047 , g | = 2.274. In the ( a, c ∗ ) plane, where Cu 2+ ions are magnetically equivalent, and in the ( a, b) plane, where the exchange interaction is great, the linewidth anisotropy is governed by anisotropic exchange and the antisymmetric exchange. In the ( b, c ∗ ) plane perpendicular to the layers, where the exchange interaction between dissimilar ions is weak, the linewidth exhibits, in addition, a contribution from magnetically inequivalent sites. The exchange interaction between dissimilar copper ions for the compound under study is determined by computer simulations of the first derivative EPR absorption spectra. Along the bisector of ( b, c ∗ ) plane, the exchange interaction is practically equal to zero whereas along the direction ( θ = π 2 , ϕ = π 4 ) of the mineral layers we have J′ = (0.16 ± 0.01) cm −1.