Subatomic resolution force microscopy reveals internal structure and adsorption sites of small iron clusters

Emmrich, Matthias; Huber, Fritz; Pielmeier, Florian; Welker, Joachim; Hofmann, Thomas; Schneiderbauer, Maximilian; Meuer, Daniel; Polesya, S.; Mankovsky, S.; Ködderitzsch, D.; Ebert, H.; Giessibl, Franz J.

doi:10.1126/science.aaa5329

Cited by 140 publications

(118 citation statements)

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“…The hcp site configuration has a slightly higher energy (by 10 meV) while the bridge and top sites are 0.28 and 0.78 eV higher in energy than the fcc adsorption site, respectively. Preferential adsorption on the fcc site is not surprising, as it has been already reported for this system [8,30]. A similarly small difference of 6 meV in favor of fcc with respect to hcp sites has been reported also for Cu adatoms on Cu(111) [31].…”

Section: A Fe Monomers On Cu(111)supporting

confidence: 51%

Multiplet features and magnetic properties of Fe on Cu(111): From single atoms to small clusters

et al. 2015

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The observation of sharp atomiclike multiplet features is unexpected for individual 3d atoms adsorbed on transition-metal surfaces. However, we show by means of x-ray absorption spectroscopy and x-ray magnetic circular dichroism that individual Fe atoms on Cu(111) exhibit such features. They are reminiscent of a low degree of hybridization, similar to 3d atoms adsorbed on alkali-metal surfaces. We determine the spin, orbital, and total magnetic moments, as well as magnetic anisotropy energy for the individual Fe atoms and for small Fe clusters that we form by increasing the coverage. The multiplet features are smoothened and the orbital moment rapidly decreases with increasing cluster size. For Fe monomers, comparison with density functional theory and multiplet calculations reveals a d 7 electronic configuration, owing to the transfer of one electron from the 4s to the 3d states.

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Section: A Fe Monomers On Cu(111)supporting

confidence: 51%

Multiplet features and magnetic properties of Fe on Cu(111): From single atoms to small clusters

et al. 2015

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“…Noncontact mode exerts the least lateral or normal forces on the sample and is very useful for measurements requiring the highest sensitivity and delicacy. 13,22,32,33 Key AFM hardware elements…”

Section: Non-contact Modementioning

confidence: 99%

High-speed atomic force microscopy for materials science

Payton

Picco

Scott

2016

International Materials Reviews

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Since its inception in 1986, the field of atomic force microscopy (AFM) has enabled surface analysis and characterisation with unparalleled resolution in a wide variety of environments. However, the technique is limited by very low sample throughput and temporal resolution making it impractical for materials science research on macro sized or time evolving samples such as the observation of corrosion. The potential of AFM sparked intense efforts to overcome these limitations shortly after its invention, and has led to the development of high-speed atomic force microscopes (HS-AFMs). Within the last 5 years the technology underpinning these instruments has matured to the point where routine imaging can achieve megapixels per second over scan areas of square millimetres, removing the limitations from AFM for industrial scale materials characterisation. This review explains the technology and looks to the future use of HS-AFMs in materials science.

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“…The metallic tip apex atom has a dipole moment induced by the Smoluchowski effect [25], whose direction is the same as that of the CO molecule adsorbed on the surface [26]. Thus in the distance regime where the electrostatic interaction between the tip and the molecule dominates, the force between them is attractive.* okabayashi@staff.kanazawa-u.ac.jp When the tip is scanned over the CO molecule, this attractive force appears as a dip (smaller value) in the frequency-shift image for each atom at its apex, i.e., the number of the attractive force minima provides the number of atoms composing the tip apex [27].In this paper, we have investigated the tip-structuredependent IETS for individual CO molecules on a Cu surface by combining STM and AFM. We have found that a tip with a single atom on its apex (single-atom tip) gives a stronger IET signal compared with a blunt tip consisting of four atoms on the apex (four-atom tip) for a CO molecule on a Cu(111) surface.…”

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confidence: 99%

“…* okabayashi@staff.kanazawa-u.ac.jp When the tip is scanned over the CO molecule, this attractive force appears as a dip (smaller value) in the frequency-shift image for each atom at its apex, i.e., the number of the attractive force minima provides the number of atoms composing the tip apex [27].…”

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confidence: 99%

Influence of atomic tip structure on the intensity of inelastic tunneling spectroscopy data analyzed by combined scanning tunneling spectroscopy, force microscopy, and density functional theory

et al. 2016

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Achieving a high intensity in inelastic scanning tunneling spectroscopy (IETS) is important for precise measurements. The intensity of the IETS signal can vary by up to a factor of 3 for various tips without an apparent reason accessible by scanning tunneling microscopy (STM) alone. Here, we show that combining STM and IETS with atomic force microscopy enables carbon monoxide front-atom identification, revealing that high IETS intensities for CO/Cu(111) are obtained for single-atom tips, while the intensity drops sharply for multiatom tips. Adsorption of the CO molecule on a Cu adatom [CO/Cu/Cu(111)] such that the molecule is elevated over the substrate strongly diminishes the tip dependence of IETS intensity, showing that an elevated position channels most of the tunneling current through the CO molecule even for multiatom tips, while a large fraction of the tunneling current bypasses the CO molecule in the case of CO/Cu(111). DOI: 10.1103/PhysRevB.93.165415 Inelastic electron tunneling spectroscopy (IETS) with scanning tunneling microscopy (STM) is an effective method to analyze the vibrational modes of a single adsorbed molecule with subnanometer lateral resolution [1,2]. The vibrational energy of a molecule on a substrate strongly depends on the surrounding environment, such as the substrate structure and composition [3]. By studying these subtle changes of the vibrational energy using STM-IETS with a molecularfunctionalized tip, it has been demonstrated that STM-IETS can provide information on the inner structure of a molecule [4,5] similarly to atomic force microscopy (AFM) [6]. These advantages of STM-IETS have accelerated research in related fields [7][8][9][10][11][12][13][14][15][16]. Owing to recent progress in the theoretical description of IETS [17][18][19][20][21][22], the qualitative understanding has been improved considerably: the symmetry of the wave functions of a tip and a molecule on a substrate and a vibrational mode of the molecule are predicted to influence the efficiency of the inelastic process (γ inel ) for the tunneling current involving the molecule. In order to discuss γ inel on the basis of the intensity of IETS, we have to consider that IETS intensity is described by the multiplication of two factors: (1) the ratio of the tunneling current passing through a molecule to the total tunneling current (I molecule /I total ) and (2) the efficiency of the inelastic process (γ inel ). These factors should in principle be affected by the geometrical structure of the substrate and of the tip.The geometrical structure of a metal tip apex can be determined by using carbon monoxide (CO) front-atom identification (COFI) provided by AFM [23,24], where the tip apex of a force sensor is probed by a CO molecule that stands upright on a metal surface [inset of Fig. 1(e)]. The metallic tip apex atom has a dipole moment induced by the Smoluchowski effect [25], whose direction is the same as that of the CO molecule adsorbed on the surface [26]. Thus in the distance regime where the electrostatic int...

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Subatomic resolution force microscopy reveals internal structure and adsorption sites of small iron clusters

Cited by 140 publications

References 46 publications

Multiplet features and magnetic properties of Fe on Cu(111): From single atoms to small clusters

Multiplet features and magnetic properties of Fe on Cu(111): From single atoms to small clusters

High-speed atomic force microscopy for materials science

Influence of atomic tip structure on the intensity of inelastic tunneling spectroscopy data analyzed by combined scanning tunneling spectroscopy, force microscopy, and density functional theory

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