Complex magnetic orders in small cobalt–benzene molecules

Abstract

Organometallic clusters based on transition metal atoms are interesting because possible applications in spintronics and quantum information. In addition to the enhanced magnetism at the nanoscale, the organic ligands may provide a natural shield again unwanted magnetic interactions with the matrices required for applications. Here we show that the organic ligands may lead to non-collinear magnetic order as well as the expected quenching of the magnetic moments. We use different density functional theory (DFT) methods to study the experimentally relevant three cobalt atoms surrounded by benzene rings (Co3Bz3). We found that the benzene rings induce a ground state with non-collinear magnetization, with the magnetic moments localized on the cobalt centers and lying on the plane formed by the three cobalt atoms. We further analyze the magnetism of such a cluster using an anisotropic Heisenberg model where the involved parameters are obtained by a comparison with the DFT results. These results may also explain the recent observation of null magnetic moment of Co3Bz + 3 . Moreover, we propose an additional experimental verification based on electron paramagnetic resonance.

Out-of-plane Enhanced Magnetic Anisotropy Energy in Ni$_{3}$Bz$_{3}$ molecule

“…The carbon-carbon bond length is 1.41 Å as found in experiments 1.40 Å61 .63 Considering the charge transfer under the Mulliken scheme, we find that for the Ni3Bz3 molecule, each nickel atoms gains more than 0.2 electrons. In total, the three nickel have 0.65 electrons, in agreement with findings for molecule Co3Bz326 . Bz 3 moleculeSI.…”

“…Magnetic effects in benzene transition metal complexes are remarkable and of particular interest for applications. For instance, non-collinear magnetic orders for Co 3 Bz 3 have been found 26 , magnetism depletion is observed in manganese-benzene compounds 27 , and it has been proposed that cobalt dimers on benzene may be magnetic storage bits 28 . Early transition atoms such as Sc, V and Ti when they are placed over benzene molecule enhance magnetic moments, others such as Mn, Fe and Co atoms decrease magnetic moments, and Ni atom magnetic moment is totally quenched 15 .…”

Strain-induced phase transition in CrI3 bilayers

“…In all our collinear calculations, we have used a Perdew-Burke-Ernzerhof (PBE) exchange 34 , and in non-collinear calculations we used the local spin-density approximation LSDA to avoid gradient divergence problems. The interstitial region increases with tensile strain and it leads to convergence issues for the PBE noncollinear calculations [35][36][37] . Detailed information about DFT parameters is provided in the supplementary material.…”

Ultrashort Mn–Mn Bonds in Organometallic Complexes

“…Similarly, many different central metal atoms have been studied, leading to alkaline-earth dimetallocenes, − transition metal dimetallocenes, − heterodinuclear compounds, , and zinc isoelectronic elements, such as Cd and Hg . Although multinuclear metallocenes of Co, Cu, Ni, and other transition metals have been described, − ,− the study of larger manganese benzene compounds is still to be done.…”