Electronic structure of aMn6(S=4)single molecule magnet grafted on Au(111)

Abstract

Single molecule magnets ͑SMMs͒ form a new class of magnetic materials consisting of identical nanoscale particles that can show magnetization in the absence of a magnetic field. We have experimentally and theoretically investigated the low-spin ͑S=4͒ member of the Mn6 SMM family, properly functionalized with two 3-thiophenecarboxylate ͑3tpc͒ ligands in order to graft it on to a Au͑111͒ surface. We report the theoretical density of states calculated within the local density approximation ͑LDA͒ scheme accounting for the on-site Coulomb repulsion ͑LDA+ U͒ for U values ranging from 0 to 8 eV. On the experimental side, by exploiting resonant photoemission at the Mn 2p edge, we were able to single out the Mn 3d derived states in the valence band energy region for a submonolayer distribution of Mn6-3tpc deposited on Au͑111͒. From the comparison between the experimentally derived 3d density of states and the theoretical one, we found that the best agreement occurs for a U value of 4 eV. From the binding energy of Mn 2p 3/2 core line, measured in situ, we also derived a value for the 2p-3d correlation energy of about 5 eV-in agreement with previous determination.

Self-consistent determination of HubbardUfor explaining the anomalous magnetism of the Gd13cluster

“…However, the value of this parameter is uncertain for nanoparticles and clusters which are characterized by large surface-to-volume ratio, reduced coordination, low dimensionality, and symmetry. In all previous theoretical studies of magnetic clusters [1,2], alloys [3][4][5], magnetic molecules [6,7], and adatoms on graphene [8], the value of U is usually taken from bulk materials and assumed to be unchanged. However, it has been reported that the value of Hubbard U for an isolated atom is about three to five times larger than an atom in a bulk solid [9].…”

Antiferromagnetic coupling of the single-molecule magnet Mn12to a ferromagnetic substrate

“…In order to build devices including magnetic molecules, stable monolayers of magnetic molecules must be formed on various substrates, and mechanisms of interactions between molecules and substrates should be understood. A great progress has been made for deposition of various SMMs, such as prototype SMM Mn 12 [3][4][5][6][7][8] , Mn 6 9 , Fe 4 10 , Cr 7 Ni 11 , and TbPc 2 12 , on metallic, semiconducting, or superconducting substrates 13 . Electronic and magnetic properties of SMMs on substrates were characterized using x-ray absorption and photoemission spectroscopy 4,6,[9][10][11] , scanning tunneling microscopy (STM) 3,7,12 , β-detected nuclear magnetic resonance 5 , and x-ray magnetic circular dichroism (XMCD) 8,10 .…”

“…A great progress has been made for deposition of various SMMs, such as prototype SMM Mn 12 [3][4][5][6][7][8] , Mn 6 9 , Fe 4 10 , Cr 7 Ni 11 , and TbPc 2 12 , on metallic, semiconducting, or superconducting substrates 13 . Electronic and magnetic properties of SMMs on substrates were characterized using x-ray absorption and photoemission spectroscopy 4,6,[9][10][11] , scanning tunneling microscopy (STM) 3,7,12 , β-detected nuclear magnetic resonance 5 , and x-ray magnetic circular dichroism (XMCD) 8,10 . On the theoretical front, the electronic structure and magnetic properties of a SMM Mn 12 monolayer adsorbed on Au were studied using densityfunctional theory (DFT) 14 .…”

Renormalization of the tunnel splitting in a rotating nanomagnet

“…(2) and (16). Renormalization of the easy-axis anisotropy by rotations can be presented in the form K ′ = K (1 − ǫ), where…”

“…Later, beams of small magnetic clusters were investigated [7][8][9][10][11][12] and more recently free magnetic nanoparticles confined within solid nanocavities have been studied 6 . Experimentalists have also worked with molecular nanomagnets deposited on surfaces [13][14][15][16] or carbon nanotubes 17 , as well as with single magnetic molecules bridged between metallic electrodes [18][19][20][21][22] . In such experiments the particles retain some mechanical freedom.…”