Spin Structure of Surface-Supported Single-Molecule Magnets from Isomorphous Replacement and X-ray Magnetic Circular Dichroism

Abstract

Surface-supported arrays of Fe(4)-type Single-Molecule Magnets retain a memory effect and are of current interest in the frame of molecule-based information storage and spintronics. To reveal the spin structure of [Fe(4)(L)(2)(dpm)(6)] (1) on Au, an isomorphous compound [Fe(3)Cr(L)(2)(dpm)(6)] was synthesized and structurally and magnetically characterized (H(3)L is tripodal ligand 11-(acetylthio)-2,2-bis(hydroxymethyl)undecan-1-ol and Hdpm is dipivaloylmethane). The new complex contains a central Cr(3+) ion and has a S = 6 ground state as opposed to S = 5 in 1. Low-temperature X-ray Magnetic Circular Dichroism studies at Fe- and Cr-L(2,3) edges revealed that the antiparallel alignment between Fe and Cr spins is preserved on surfaces. Moreover, the different Fe-L(2,3) spectral features found in the homo- and heterometallic species disclose the opposing contribution of the central Fe(3+) ion in the former compound, proving that its ferrimagnetic spin structure is retained on surfaces.

Grafting Single Molecule Magnets on Gold Nanoparticles

“…The maximum XMCD amplitude at 709.1 eV (ca. 40%) and the vanishing signal at 707.8 eV are considered fingerprints of the ferrimagnetic spin structure schematized in Figure a, where the central and peripheral iron ions provide opposing magnetic contributions . Our synchrotron investigation thus indicates that Au‐NPs are capped by intact SMMs.…”

Origin and spectroscopic determination of trigonal anisotropy in a heteronuclear single-molecule magnet

“…40,41 In an effort to synthesize heterometallic clusters with the same topology, in the past few years we have devised a procedure to replace the central iron(III) with a different tripositive metal ion M. The first synthetic method we described was based on a one-pot reaction and resulted in a solid solution of Fe 3 M and Fe 4 . 42,43 Much better suited for detailed spectroscopic studies are samples prepared through a three-step synthetic approach, which reduces the amount of Fe 4 to below the detection limit. 44 Of particular interest among these new heterometallic systems are Fe 3 Cr complexes characterized by an S = 6 ground state and an axial zero field splitting (zfs) parameter D ≅ -0.18 cm -1 .…”

Field-induced internal Fe and Ln spin reorientation in butterfly{Fe3LnO2}(LnBadía-Romano1, Bartolomé2, Bartolomé3 et al. 2013Phys. Rev. B222140View full textAdd to dashboardCite

“…The XMCD measured at the Fe and Cr L 2,3 edges on Fe 3 Cr tripod clusters, with a central Cr atom, deposited on Au showed that the antiparallel alignment between Fe and Cr spins is preserved on surfaces. 36 Cr 7 Ni ring spin clusters assembled on a Au substrate have also been investigated using XMCD technique as a function of temperature and field, demonstrating that the relative orientation between the Cr and the Ni magnetic moments changes from antiparallel to parallel with increasing temperature. 37 In addition, SMM behavior has also been proven in the endohedral system DySc 2 N@C 80 with complementary XMCD and SQUID measurements.…”