title: Local spin density in the Cr7Ni antiferromagnetic molecular ring and 53Cr-NMR.
abstract: We present (53)Cr-NMR spectra collected at low temperature in a single crystal of the heterometallic antiferromagnetic (AF) ring Cr(7)Ni in the S = 1/2 ground state with the aim of establishing the distribution of the local electronic moment in the ring. Due to the poor S/N we observed only one signal which is ascribed to three almost equivalent (53)Cr nuclei in the ring. The calculated spin density in Cr(7)Ni in the ground state, with the applied magnetic field both parallel and perpendicular to the plane of the ring, turns out to be AF staggered with the greatest component of the local spin <s> for the Cr(3+) ions next to the Ni(2+) ion. The (53)Cr-NMR frequency was found to be in good agreement with the local spin density calculated theoretically by assuming a core polarization field of H(cp) = - 11 T/μ(B) for both orientations, close to the value found previously in Cr(7)Cd. The observed orientation dependence of the local spin moments is well reproduced by the theoretical calculation and evidences the importance of single-ion and dipolar anisotropies.
authors.affiliation: CNISM and Department of Physics, Università degli Studi di Pavia, I-27100 Pavia, Italy.
authors.forename: C M
authors.initials: CM
authors.lastname: Casadei
authors.forename: L
authors.initials: L
authors.lastname: Bordonali
authors.forename: Y
authors.initials: Y
authors.lastname: Furukawa
authors.forename: F
authors.initials: F
authors.lastname: Borsa
authors.forename: E
authors.initials: E
authors.lastname: Garlatti
authors.forename: A
authors.initials: A
authors.lastname: Lascialfari
authors.forename: S
authors.initials: S
authors.lastname: Carretta
authors.forename: S
authors.initials: S
authors.lastname: Sanna
authors.forename: G
authors.initials: G
authors.lastname: Timco
authors.forename: R
authors.initials: R
authors.lastname: Winpenny
mesh_terms: D002858:Chromium Alloys / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008422:Materials Testing; D013113:Spin Labels
chemical_list: D002858:Chromium Alloys; D013113:Spin Labels