Huge magnetically coupled orbital moments of Co porphyrin molecules and their control by CO adsorption

Hermanns, Christian Felix; Bernien, Matthias; Krüger, Alex; Walter, Waldemar; Chang, Yin-Ming; Weschke, E.; Kuch, W.

doi:10.1103/physrevb.88.104420

Cited by 21 publications

(23 citation statements)

References 39 publications

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“…For example, CoOEP was found to engage in antiferromagnetic coupling to Ni/W(1 1 0), from which it was separated by a graphene layer. Besides the spin magnetic moment, a large in-plane orbital magnetic moment was observed, which was also antiferromagnetically coupled to the Ni spin [681,682]. Similar observations were made for CoOEP on graphene/Ni(1 1 1) [683].…”

Section: Adsorption On Metal Substrates Covered With An Interlayersupporting

confidence: 79%

“…For CoOEP on graphene/Ni/W (1 1 0), it was found that the large in-plane orbital magnetic moment, which was antiferromagnetically coupled to the Ni spin, was reversibly reduced upon attachment of CO to the Co ion. This effect was explained with a CO-induced change of the ligand field, which is one of the factors that determine the orbital moment [682].…”

Section: Influence Of the Axial Ligand On The Spin: Surface Spintransmentioning

confidence: 99%

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Surface chemistry of porphyrins and phthalocyanines

Gottfried

2015

Surface Science Reports

572

586

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Section: Adsorption On Metal Substrates Covered With An Interlayersupporting

confidence: 79%

Section: Influence Of the Axial Ligand On The Spin: Surface Spintransmentioning

confidence: 99%

Surface chemistry of porphyrins and phthalocyanines

Gottfried

2015

Surface Science Reports

572

586

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“…DOI: 10.1103/PhysRevLett.114.106807 PACS numbers: 73.22.-f, 32.10.Dk, 75.30.Gw, 75.75.-c Individual surface-adsorbed magnetic atoms exhibit remarkably large orbital moments and anisotropies [1][2][3][4][5]. Like in adsorbed single ion molecules [6][7][8][9][10], their chemical environment can be tailored through exposure to reactive molecules, thus allowing the tuning of their magnetic properties [11]. Among the wealth of available molecules, H 2 is of particular interest.…”

mentioning

confidence: 99%

“…Like in adsorbed single ion molecules [6][7][8][9][10], their chemical environment can be tailored through exposure to reactive molecules, thus allowing the tuning of their magnetic properties [11]. Among the wealth of available molecules, H 2 is of particular interest.…”

mentioning

confidence: 99%

Controlling the Spin of Co Atoms on Pt(111) by Hydrogen Adsorption

et al. 2015

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We investigate the effect of H adsorption on the magnetic properties of individual Co atoms on Pt(111) with scanning tunneling microscopy. For pristine Co atoms, we detect no inelastic features in the tunnel spectra. Conversely, CoH and CoH 2 show a number of low-energy vibrational features in their differential conductance identified by isotope substitution. Only the fcc-adsorbed species present conductance steps of magnetic origin, with a field splitting identifying their effective spin as S eff ¼ 2 for CoH and 3=2 for CoH 2 . The exposure to H 2 and desorption through tunnel electrons allow the reversible control of the spin in halfinteger steps. Because of the presence of the surface, the hydrogen-induced spin increase is opposite to the spin sequence of CoH n molecules in the gas phase. DOI: 10.1103/PhysRevLett.114.106807 PACS numbers: 73.22.-f, 32.10.Dk, 75.30.Gw, 75.75.-c Individual surface-adsorbed magnetic atoms exhibit remarkably large orbital moments and anisotropies [1][2][3][4][5]. Like in adsorbed single ion molecules [6][7][8][9][10], their chemical environment can be tailored through exposure to reactive molecules, thus allowing the tuning of their magnetic properties [11]. Among the wealth of available molecules, H 2 is of particular interest. The high reactivity of adsorbed transition metal atoms promotes the dissociation of the H 2 molecule and the formation of metal-H n complexes (n ¼ 1; 2; 3), even at cryogenic temperatures [2,[12][13][14][15][16]. Moreover, the relatively small H desorption barrier allows the reversible control of the number of adsorbed hydrogen atoms, e.g., by desorption through electrons from a scanning tunneling microscopy (STM) tip and adsorption from the gas phase [2,15].The magnetic properties of gas phase transition-metal-H n complexes have been studied by means of ab initio calculations. These calculations reveal a significant change of the magnetic properties through hydrogenation, with a clear tendency of decreasing spin with increasing number of H atoms [17][18][19]. This results from the antiparallel spin alignment between metal and H. In particular, for the case of Co, the spin S ¼ 3=2 of the free atom is reduced to 1 and 1=2 upon the adsorption of one and two hydrogen atoms, respectively [17][18][19].The effect of hydrogen adsorption on the spin of surfaceadsorbed magnetic atoms is largely unknown. Hints that the spin possibly changes upon H adsorption can be inferred from the H-induced appearance [14] or disappearance [13,15] of the Kondo effect. However, for S > 1=2 this can also be caused by a change in magnetic anisotropy [20].Neither the spin nor the anisotropy have been measured in Refs. [13][14][15], while for Co=graphene=Ptð111Þ the adsorption of three H atoms was shown to reduce the anisotropy energy [2].Here we demonstrate that the spin of individual Co adatoms on Pt(111) can be controlled through hydrogenation. This process is reversible as the H atoms can be desorbed one by one with the STM tip. Clean cobalt atoms on Pt(111) have S ≈ 1, an out-...

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“…However, intrinsic spin switches such as spin-crossover complexes so far suffer from fragmentation or loss of functionality upon adsorption on metal surfaces with rare exceptions [6][7][8][9] . Robust metal-organic platforms, on the other hand, rely on external axial ligands to induce spin switching [10][11][12][13][14] . Here we integrate a spin switching functionality into robust complexes relying on the mechanical movement of an axial ligand strapped to the porphyrin ring.…”

mentioning

confidence: 99%