title: Spin configuration in the 1/3 magnetization plateau of azurite determined by NMR.
abstract: High magnetic field (63,65)Cu NMR spectra were used to determine the local spin polarization in the 1/3 magnetization plateau of azurite, Cu3(CO3)(2)(OH)(2), which is a model system for the distorted diamond antiferromagnetic spin-1/2 chain. The spin part of the hyperfine field of the Cu2 (dimer) sites is found to be field independent, negative and strongly anisotropic, corresponding to approximately 10% of fully polarized spin in a d orbital. This is close to the expected configuration of the quantum plateau, where a singlet state is stabilized on the dimer. However, the observed nonzero spin polarization points to some triplet admixture, induced by strong asymmetry of the diamond bonds J1 and J3.
authors.affiliation: Grenoble High Magnetic Field Laboratory, 38042 Grenoble Cedex 9, France.
authors.forename: F
authors.initials: F
authors.lastname: Aimo
authors.forename: S
authors.initials: S
authors.lastname: Krämer
authors.forename: M
authors.initials: M
authors.lastname: Klanjsek
authors.forename: M
authors.initials: M
authors.lastname: Horvatić
authors.forename: C
authors.initials: C
authors.lastname: Berthier
authors.forename: H
authors.initials: H
authors.lastname: Kikuchi