Atomic scale control of single molecule charging

Mikaelian, Gareguin; Ogawa, Norio; Tu, Xiuwen; Ho, W.

doi:10.1063/1.2174961

Cited by 39 publications

(38 citation statements)

References 27 publications

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“…84,398,399 In contrast to metal clusters, complex organic molecules have another degree of freedom that interferes with the charging behavior, namely their structural conformation. The occurrence of charge transfer is therefore not only governed by the energy position of the molecular affinity levels with respect to the Fermi energy, but depends additionally on the actual binding geometry of the molecule and its coupling strength to the support.…”

Section: Molecular Chargingmentioning

confidence: 99%

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Properties of oxide thin films and their adsorption behavior studied by scanning tunneling microscopy and conductance spectroscopy

Nilius

2009

Surface Science Reports

219

233

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The preparation of thin oxide films on metal supports is a versatile approach to explore the properties of oxide materials that are otherwise inaccessible to most surface science techniques due to their insulating nature. Although substantial progress has been made in the characterization of oxide surfaces with spatially averaging techniques, a local view is often essential to provide comprehensive understanding of such systems. The scanning tunneling microscope (STM) is a powerful tool to obtain atomic-scale information on the growth behavior of oxide films, the resulting surface morphology and defect structure.

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Section: Molecular Chargingmentioning

confidence: 99%

“…84,399 In the unbiased STM junction, the molecule adsorbs in the neutral charge state on the surface. It is imaged as a small entity with cross-like shape at low sample bias, indicating the absence of molecular orbitals for electron transport around E F .…”

Section: Molecular Chargingmentioning

confidence: 99%

Properties of oxide thin films and their adsorption behavior studied by scanning tunneling microscopy and conductance spectroscopy

Nilius

2009

Surface Science Reports

219

233

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“…To explain this novel manifestation of magnetically sensitive NDR (Supplementary Discussion), we suggest a mechanism based on transient charging that arises from the occupation of molecular resonances [29]. This results in a change in the tunnelling rates through the molecule that can increase or decrease the differential conductance, with the latter resulting in NDR.…”

mentioning

confidence: 99%

Tunable magnetoresistance in an asymmetrically coupled single-molecule junction

et al. 2015

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Phenomena that are highly sensitive to magnetic fields can be exploited in sensors and non-volatile memories [1]. The scaling of such phenomena down to the single molecule level [2, 3] may enable novel spintronic devices [4]. Here we report magnetoresistance in a single molecule junction arising from negative differential resistance that shifts in a magnetic field at a rate two orders of magnitude larger than Zeeman shifts. This sensitivity to the magnetic field produces two voltage-tunable forms of magnetoresistance, which can be selected via the applied bias. The negative differential resistance is caused by transient charging [5][6][7] of an iron phthalocyanine (FePc) molecule on a single layer of copper nitride (Cu 2 N) on a Cu(001) surface, and occurs at voltages corresponding to the alignment of sharp resonances in the filled and empty molecular states with the Cu(001) Fermi energy. An asymmetric voltage-divider effect enhances the apparent voltage shift of the negative differential resistance with magnetic field, which inherently is on the scale of the Zeeman energy [8]. These results illustrate the impact that asymmetric coupling to metallic electrodes can have on transport through molecules, and highlight how this coupling can be used to develop molecular spintronic applications.Research into magnetoresistance [9, 10] has been driven by the widespread use of giant magnetoresistance (GMR) sensors in hard drives as well as other applications such as magnetoresistive random access memory (MRAM) [1]. To reach even higher storage densities, research has begun to concentrate on magnetoresistance at the atomic scale [2, 3, 11]. For a single molecule, however, the small area for enclosing flux and modest energy scales associated with electronic Zeeman shifts typically make it difficult to tune magnetoresistive phenomena with an external magnetic field.Another electron transport phenomenon with technological relevance is negative differential resistance (NDR) [5, 7,[12][13][14][15][16][17][18][19], in which an increase in voltage causes a decrease in current. Commercial devices, such as the resonant tunnelling diode, utilise these regions in specialised applications [20, 21]. Various mechanisms cause NDR at the atomic scale [5, 7,[12][13][14][15][16][17][18][19], though none are expected to have a magnetic field dependence that would shift the NDR on a scale larger than the Zeeman energy.Using low temperature scanning tunnelling microscopy (STM) (see Supplementary Methods), we observe an NDR effect for FePc molecules placed in a vacuum junction on top of 2 a Cu(001) surface capped with a single layer of Cu 2 N (Fig. 1). Cu 2 N is a thin insulator that can decouple the spins of magnetic atoms from the underlying surface [22]; FePc is a magnetic molecule that can be easily sublimed [23][24][25] and is observed to have interesting magnetic properties on thin insulating layers [26]. On Cu 2 N, FePc is centred above both Cu and N sites. The two binding sites can be differentiated using atomically resolved imaging a...

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“…Ultrathin metal oxide layers have been used to reduce the electronic interaction between molecules and substrates allowing the observation of fluorescence [4], vibronic states [5], and charging of isolated molecules [6]. Franke et al have recently reduced the electronic coupling of C 60 with a metal surface by locking and lifting each fullerene with a second molecular species [7].…”

Section: Introductionmentioning

confidence: 99%

Stabilization of bimolecular islands on ultrathin NaCl films by a vicinal substrate

et al. 2009

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a b s t r a c tThe structure of ultrathin NaCl films on Au(1 1 1) and on Au(11 12 12), as well as the one of bimolecular 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) and 1,4-bis-(2,4-diamino-1,3,5,-triazine)-benzene (BDATB) islands on NaCl films on both surfaces have been studied with a low-temperature scanning tunnelling microscope. We show that intermixed bimolecular assemblies based on selective three-fold hydrogen-bonding (H-bonding), that have previously been observed on Au(1 1 1) and on Au(11 12 12), can also be stabilized on insulating NaCl films on Au, however, only if these films are grown on Au(11 12 12) and not on Au(1 1 1). The behaviour of the heterocomplex structures is found to be largely influenced by the structural properties of the underlying substrate and by the number of NaCl layers. On a partly NaCl-covered Au(1 1 1) surface, the excess of molecules after completion of the first layer on Au prefers to form a second molecular layer based on ordered heterocomplex structures rather than to adsorb on the NaCl islands. The use of a vicinal surface together with the strong cohesion characteristic of the NaCl film introduces smooth elastic deformations on the NaCl(0 0 1) plane. As a consequence, the periodically modified structure of the overlayer provides preferential binding sites and allows adsorption of two-dimensional molecular structures. In contrast to what is observed on Au(11 12 12), the molecular domains on the NaCl film do not follow the Au step directions, but the NaCl(0 0 1) high symmetry directions. Our results provide a strategy to increase the adsorption energy of flat molecules on insulating layers by choosing a vicinal metal substrate.

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Atomic scale control of single molecule charging

Cited by 39 publications

References 27 publications

Properties of oxide thin films and their adsorption behavior studied by scanning tunneling microscopy and conductance spectroscopy

Properties of oxide thin films and their adsorption behavior studied by scanning tunneling microscopy and conductance spectroscopy

Tunable magnetoresistance in an asymmetrically coupled single-molecule junction

Stabilization of bimolecular islands on ultrathin NaCl films by a vicinal substrate

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