title: Spin Helicity in Chiral Lanthanide Chains.
abstract: We report here the determination of the helical spin structure of three Ln-based chiral chains of the formula [Ln(Hnic)(nic)2(NO3)]n(Hnic = nicotinic acid; Ln = Tb, Dy, and Er) by means of cantilever torque magnetometry. While the Dy and Er derivatives are strongly axial (easy-axis and easy-plane anisotropy, respectively), the Tb derivative is characterized by a remarkable rhombicity. In agreement with these findings, alternating-current susceptibility reveals slow magnetic relaxation only in the Dy derivative. Dilution of DyIIIions in the diamagnetic Y-based analogue shows that the weak ferromagnetic intrachain interactions do not contribute significantly to the energy barrier for the reversal of magnetization, which is better described as a single-ion process. Single crystals of the two enantiomers of the Dy derivative have also been investigated using hard X-ray synchrotron radiation at the L-edge of the metal revealing optical activity although with negligible involvement of the 4f electrons of the DyIIIion.
authors.affiliation: Institute of Nanotechnology, Karlsruhe Institute of Technology , Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Ionut
authors.initials: I
authors.lastname: Mihalcea
authors.affiliation: Department of Chemistry, "U. Schiff" Università di Firenze and INSTM RU Firenze via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Perfetti
authors.affiliation: Department of Chemistry, "U. Schiff" Università di Firenze and INSTM RU Firenze via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy.|Department of Chemistry and Industrial Chemistry, University of Pisa , via Moruzzi 3, 56124 Pisa, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Pineider
authors.affiliation: Department of Chemistry, "U. Schiff" Università di Firenze and INSTM RU Firenze via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Tesi
authors.affiliation: Institute of Inorganic Chemistry, Karlsruhe Institute of Technology , Engesserstrasse 15, D-76131 Karlsruhe, Germany.
authors.forename: Valeriu
authors.initials: V
authors.lastname: Mereacre
authors.affiliation: European Synchrotron Radiation Facility (ESRF) , 38043 Grenoble, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Wilhelm
authors.affiliation: European Synchrotron Radiation Facility (ESRF) , 38043 Grenoble, France.
authors.forename: Andrei
authors.initials: A
authors.lastname: Rogalev
authors.affiliation: Institute of Inorganic Chemistry, Karlsruhe Institute of Technology , Engesserstrasse 15, D-76131 Karlsruhe, Germany.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Anson
authors.affiliation: Institute of Nanotechnology, Karlsruhe Institute of Technology , Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany.|Institute of Inorganic Chemistry, Karlsruhe Institute of Technology , Engesserstrasse 15, D-76131 Karlsruhe, Germany.
authors.forename: Annie K
authors.initials: AK
authors.lastname: Powell
authors.affiliation: Department of Chemistry, "U. Schiff" Università di Firenze and INSTM RU Firenze via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Sessoli