Local Magnetic Structure of Layered Compounds Cu2(OD)3X with Exchangeable Acid Anion X Studied by Solid State High Resolution Deuterium NMR

Abstract

The microscopic magnetic local structure of Botallackite-type layer structured compounds Cu2(OD)3X (X = NO3 − and HCOO−) exhibiting a nonequilateral planar triangular magnetic lattice was determined by the solid-state high resolution deuterium NMR of deuterated hydroxy groups in the high temperature region above 190 K. The magnetic interactions in a copper ion layer were probed by the paramagnetic NMR shifts of the two chemically distinct hydroxy groups. Isotropic NMR shift of each hydroxy group showed different temperature dependence, suggesting non-uniform magnetic interaction. The magnetic interaction in the copper layer could be decomposed into a sum of 1D-Heisenberg ferro- and antiferromagnetic chains in the high temperature region. Two distinct copper chains with ferro- and antiferromagnetic exchange interactions J= ± 19 ± 11 and − 21 ± 3 K were found for x = NO3− from the temperature dependence of the two distinct NMR signals, while J = ± 13 ± 7 and − 13 ± 5 K for x = HCOO−. The derived values of J almost reproduced the temperature behavior of the magnetic susceptibility χiA T vs. T.