High Field ESR Study of the New Low Dimensional S=1/2 System: Cu(NO3)2⋅H2O

Abstract

Cu(NO3)2⋅H2O is a new S=1/2 system based on transition metal nitrates and contains two-dimensional Cu2+ (S=1/2) layers. We studied single crystalline samples by means of high field (HF) ESR and NMR. Cu2+ HF-ESR and 1H-NMR data reveal pronounced spin-spin correlations at temperatures much higher than the antiferromagnetic ordering temperature TN∼3.6 K. These observations clearly suggest a two-dimensional character of magnetic interactions in Cu(NO3)2⋅H2O. We discuss the obtained results by considering the possible exchange paths between inequivalent Cu-sites in this compound.