Premium
Magnetic Anisotropy of Cr 7 Ni Spin Clusters on Surfaces
Author(s) -
Corradini Valdis,
Ghirri Alberto,
Garlatti Elena,
Biagi Roberto,
De Renzi Valentina,
del Pennino Umberto,
Bellini Valerio,
Carretta Stefano,
Santini Paolo,
Timco Grigore,
Winpenny Richard E. P.,
Affronte Marco
Publication year - 2012
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201200478
Subject(s) - magnetization , magnetic anisotropy , condensed matter physics , materials science , anisotropy , magnetic circular dichroism , magnetic moment , density functional theory , magnetic field , physics , spectral line , optics , quantum mechanics , astronomy
Abstract The problem of the experimental and theoretical determination of magnetic anisotropy in isolated molecular spin clusters is addressed here. To this end, the case of molecular Cr 7 Ni rings sublimated in ultrahigh vacuum conditions and assembled in an ordered fashion on Au(111) surface is addressed and investigated using X‐ray magnetic dichroism (XMCD) and theoretical calculations. Fixing the experimental conditions at a temperature T = 8 K and a magnetic field of 5 T, the angular‐dependence of the dichroic signal reveals an easy‐axis anisotropy for the Ni magnetization along the direction perpendicular to the ring while the magnetization of the whole Cr 7 Ni molecule is preferentially aligned within the ring plane. These features are well reproduced by spin Hamiltonian simulations, which reflect the character of the S = 3/2 first excited multiplet, dominating at T = 8 K and 5 T. Density functional theory (DFT) calculations show that local spin orbit interactions determine an easy axis anisotropy at the Ni site while the Cr magnetic moment turns out to be more isotropic. This is the first direct observation of the interplay between the single ion and the overall magnetic anisotropy in complex (polynuclear) molecular systems.