Electron transport through single phthalocyanine molecules studied using scanning tunneling microscopy

Takács, A. F.; Witt, F.; Schmaus, Stefan; Balashov, T.; Bowen, M.; Beaurepaire, E.; Wulfhekel, Wulf

doi:10.1103/physrevb.78.233404

Cited by 51 publications

(63 citation statements)

References 19 publications

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“…As supported by a phenomenological model, this latter result could underscore how, due to molecular chemisorption onto a transition metal surface, the OS's molecules at the interface may exhibit a molecular orbital (MO) at E F 6 that extends the electrode conduction onto the first molecular monolayer(ML)7. Due to exchange-split bands, the unequal density of states (DOS) of the two spin populations at E F in the FM is then believed to lead to a spin-selective broadening of this MO5, i.e.…”

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confidence: 87%

Direct observation of a highly spin-polarized organic spinterface at room temperature

Djeghloul

Ibrahim

Cantoni

et al. 2013

Sci Rep

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128

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Organic semiconductors constitute promising candidates toward large-scale electronic circuits that are entirely spintronics-driven. Toward this goal, tunneling magnetoresistance values above 300% at low temperature suggested the presence of highly spin-polarized device interfaces. However, such spinterfaces have not been observed directly, let alone at room temperature. Thanks to experiments and theory on the model spinterface between phthalocyanine molecules and a Co single crystal surface, we clearly evidence a highly efficient spinterface. Spin-polarised direct and inverse photoemission experiments reveal a high degree of spin polarisation at room temperature at this interface. We measured a magnetic moment on the molecule's nitrogen π orbitals, which substantiates an ab-initio theoretical description of highly spin-polarised charge conduction across the interface due to differing spinterface formation mechanisms in each spin channel. We propose, through this example, a recipe to engineer simple organic-inorganic interfaces with remarkable spintronic properties that can endure well above room temperature.

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confidence: 87%

Direct observation of a highly spin-polarized organic spinterface at room temperature

Djeghloul

Ibrahim

Cantoni

et al. 2013

Sci Rep

Self Cite

128

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“…In fine, the negative sign of the TMR observed can be explained by a strong coupling at the lower interface that inverts the spin polarization. Indeed, this would be supported by STM experiments on the same interface system (CoPc on a Co electrode) that have revealed that a strong coupling (chemisorption) induces shifts in the molecular states to the Fermi level [9] and leads to an inversion of the spin polarization [12,14,30]. The fact that this spin polarization inversion does not occur at the top interface would then be explained by a differing strength of hybridization [4] when the metal is deposited on top of the molecules.…”

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confidence: 90%

“…The understanding of the magnetotransport experiments additionally requires a specific Co=CoPc interface electronic and magnetic coupling defining a new effective electrode that would integrate the first molecular layer [4]. This is indeed the case as witnessed from scanning tunneling spectroscopy experiments on such interfaces [9]. Given the antiferromagnetic ordering of CoPc, this effective electrode, which integrates the first molecular layer, is then antiferromagnetically coupled to the other molecular layers.…”

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confidence: 96%

“…Contrary to Alq 3 , MPc molecules form a well-organized structure once deposited on a surface [8]. Furthermore, it has been shown that the electronic properties of metal-MPc interfaces could be crafted by changing the metallic surface or the center ion [9][10][11]. Spin-dependent hybridizations in MPc ðCoPc; H 2 Pc; MnPc; FePc; orCuPcÞ on FM surfaces (Fe, Co) have been unveiled by spin-polarized STM [12][13][14][15] or x-ray spectroscopy studies [10,11,16], making these molecules very promising for molecular spintronics.…”

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confidence: 99%

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Unidirectional Spin-Dependent Molecule-Ferromagnet Hybridized States Anisotropy in Cobalt Phthalocyanine Based Magnetic Tunnel Junctions

et al. 2015

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Organic or molecular spintronics is a rising field of research at the frontier between condensed matter physics and chemistry. It aims to mix spin physics and the richness of chemistry towards designing new properties for spin electronics devices through engineering at the molecular scale. Beyond the expectation of a long spin lifetime, molecules can be also used to tailor the spin polarization of the injected current through the spin-dependent hybridization between molecules and ferromagnetic electrodes. In this Letter, we provide direct evidence of a hybrid interface spin polarization reversal due to the differing hybridization between phthalocyanine molecules and each cobalt electrode in Co/CoPc/Co magnetic tunnel junctions. Tunnel magnetoresistance and anisotropic tunnel magnetoresistance experiments show that interfacial hybridized electronic states have a unidirectional anisotropy that can be controlled by an electric field and that spin hybridization at the bottom and top interfaces differ, leading to an inverse tunnel magnetoresistance.

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“…12 Energy level alignment at organic semiconductor interfaces of 3d-transition metal phthalocyanines was systematically investigated by Grobosch et al.. 13 Transport and vibration properties of MPc-metal substrate systems were also studied. [14][15][16][17] In these studies, quantum mechanical calculations based on density functional theory (DFT) were employed to understand and predict the interface properties of MPc-metal systems. Electronic structures of free MPc molecules with 3d-transition metal were studied with various exchange correlation functionals.…”

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confidence: 99%

Binding configuration, electronic structure, and magnetic properties of metal phthalocyanines on a Au(111) surface studied withab initiocalculations

Zhang

Gao

2011

Phys. Rev. B

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Binding configurations, interface electronic structures, and magnetic properties of 3d-transition metal phthalocyanine (MPc, where M=Mn, Fe, Co, Ni, Cu or Zn) molecular systems on Au(111) substrate, are systematically investigated with first-principles density functional theory (DFT) calculations using PW91 exchange-correlation functional. We also calculated the corresponding properties of free standing molecules and did comparisons between these two cases. It is found that MnPc, FePc and CoPc have a stronger binding than that of NiPc, CuPc and ZnPc.For the magnetic property of the MPc molecules, it is not affected after the molecular adsorption, except for CoPc. In addition, for the adsorption properties of FePc on Au(111), we find out that the low adsorption energy and small energy differences between different configurations allow the FePc molecules to diffuse on Au (111) substrate easily at certain temperatures.

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Electron transport through single phthalocyanine molecules studied using scanning tunneling microscopy

Cited by 51 publications

References 19 publications

Direct observation of a highly spin-polarized organic spinterface at room temperature

Direct observation of a highly spin-polarized organic spinterface at room temperature

Unidirectional Spin-Dependent Molecule-Ferromagnet Hybridized States Anisotropy in Cobalt Phthalocyanine Based Magnetic Tunnel Junctions

Binding configuration, electronic structure, and magnetic properties of metal phthalocyanines on a Au(111) surface studied withab initiocalculations

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