Electrostatic Force Microscopy on Oriented Graphite Surfaces: Coexistence of Insulating and Conducting Behaviors

Lu, Yonghua; Muñoz, M. C.; Steplecaru, C. S.; Cheng, Hao; Bai, Ming Hua; Garcı́a, N.; Schindler, Kathrin; Esquinazi, P.

doi:10.1103/physrevlett.97.076805

Cited by 71 publications

(31 citation statements)

References 20 publications

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“…It has recently been demonstrated that in HOPG samples, regions with "metaliclike" and "insulatinglike" behaviors coexist and the internal structure of bulk HOPG samples is not homogeneous in the micrometer range. 17 This find suggests that HOPG samples may have to be considered as composite materials. In carbon-composite materials, apparent negative resistance has been measured by four terminal technique, which has been explained by the backflow of electrons in the unexpected direction relative to the applied voltage gradient.…”

Section: Fig 3 (A)mentioning

confidence: 99%

Possible room temperature superconductivity in conductors obtained by bringing alkanes into contact with a graphite surface

Kawashima

2013

AIP Advances

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In 1986, a cuprate superconductor (Ba-La-Cu-O system) having a critical temperature which goes over the BCS limit (~30 K) was discovered and then a cuprate superconductor (Y-Ba-Cu-O system) with a critical temperature higher than 77 K was discovered. Furthermore, a Hg-based cuprate with a critical temperature of 133 K was found. The 133 K is still the highest critical temperature of conventional superconductors under atmospheric pressure. We have shown that materials obtained by bringing n-alkanes into contact with graphite are capable of conducting electricity with almost no energy loss at room temperature. We here report that the sudden jump in resistance showing a phase transition is observed in the materials during heating by two-probe resistance measurement. The measured critical temperatures of the materials consisting of pitch-based graphite fibers and n-alkanes having 7-16 carbon atoms range from 363.08 to 504.24 K and the transition widths range between 0.15 and 3.01 K. We also demonstrate that superconductors with critical temperatures beyond 504 K are obtained by alkanes with 16 or more carbon atoms.

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Section: Fig 3 (A)mentioning

confidence: 99%

Possible room temperature superconductivity in conductors obtained by bringing alkanes into contact with a graphite surface

Kawashima

2013

AIP Advances

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“…EFS is performed at well-defined stationary points by sweeping V probe (i.e., −3 to +3 V) with mV resolution, while recording the corresponding phase change Δφ [18,20,113]. The V 2 term in Equation (1) leads to a parabolic response as a result of attractive and repulsive nature of separated charges (Figure 14a).…”

Section: Electrostatic Force Spectroscopy (Efs)mentioning

confidence: 99%

“…on the nanoscale. While the EFM method allows mainly qualitative mapping of the surface potential [7,[18][19][20], the KPFM technique provides quantitative values for the work function difference, Φ s = Φ probe -eV CPD , where Φ s and Φ probe are work functions of the surface and probe, respectively, and V CPD is the contact potential difference directly measured by KPFM. Using KPFM method, both exfoliated [21] and epitaxial [22][23][24] graphene with different number of layers has been studied by various groups.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial Graphene and Graphene–Based Devices Studied by Electrical Scanning Probe Microscopy

2013

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Abstract:We present local electrical characterization of epitaxial graphene grown on both Si-and C-faces of 4H-SiC using Electrostatic Force Microscopy and Kelvin Probe Force Microscopy in ambient conditions and at elevated temperatures. These techniques provide a straightforward identification of graphene domains with various thicknesses on the substrate where topographical determination is hindered by adsorbates and SiC terraces. We also use Electrostatic Force Spectroscopy which allows quantitative surface potential measurements with high spatial resolution. Using these techniques, we study evolution of a layer of atmospheric water as a function of temperature, which is accompanied by a significant change of the absolute surface potential difference. We show that the nanoscale wettability of the material is strongly dependent on the number of graphene layers, where hydrophobicity increases with graphene thickness. We also use micron-sized graphene Hall bars with gold electrodes to calibrate work function of the electrically conductive probe and precisely and quantitatively define the work functions for single-and double-layer graphene.

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“…[22][23][24][25][26][27] However, surface probing techniques capable of atomic resolution make studying surface defects relatively easier. Using scanning tunneling microscopy, [12][13][14][15][16] scanning tunneling spectroscopy, 17,28 atomic force microscopy, 15,29 electrostatic force microscopy, 30 magnetic forces microscopy, 10,11,31 and transmission electron microscopy 9,32 one can visualize both the formation and evolution of defects populations on the surface of graphite [10][11][12][13]15,16,[29][30][31] and related nanostructures. 9 As a result, the generation of single vacancies ͑V͒, 13,16,21,28,[33][34][35][36][37][38][39] multivacancies, 16,21 interstitials ͑I͒, 21,33,35,36,40,…”

Section: Introductionmentioning

confidence: 99%

Structure and properties of surface and subsurface defects in graphite accounting for van der Waals and spin-polarization effects

2010

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The geometries, formation energies, and diffusion barriers of surface and subsurface intrinsic defects in graphite are calculated using spin-polarized density-functional theory and the generalized gradient approximation with a semiempirical van der Waals ͑vdW͒ correction for dispersion interactions. The calculated formation energies and diffusion barriers of subsurface interstitial ͑I͒ atoms deviate qualitatively and quantitatively from those of surface adatoms. The same trend is found also for subsurface and adatom clusters ͑I 2 ,I 3 ͒. In spite of the semiquantitative agreement on the optimized geometries, the formation energies and diffusion barriers of surface and subsurface vacancies ͑V͒, divacancies ͑VV͒, and intimate ͑I-V͒ Frenkel pairs differ significantly from the values for the analogous defects in the bulk of graphite. This suggests limited transferability of the bulk and subsurface defect models to the surface of graphite. These findings are rationalized in terms of the balance between the covalent and vdW interaction terms at the surface, subsurface, and bulk of graphite. Finally, pairing of individual defects ͑adatoms, I and V͒ is calculated to be energetically advantageous both on the surface and in the subsurface regions. This process is shown to either saturate residual dangling bonds or produce singlet spin states, thus contributing to the quenching of residual spin polarization from damaged graphite surfaces.

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Electrostatic Force Microscopy on Oriented Graphite Surfaces: Coexistence of Insulating and Conducting Behaviors

Cited by 71 publications

References 20 publications

Possible room temperature superconductivity in conductors obtained by bringing alkanes into contact with a graphite surface

Possible room temperature superconductivity in conductors obtained by bringing alkanes into contact with a graphite surface

Epitaxial Graphene and Graphene–Based Devices Studied by Electrical Scanning Probe Microscopy

Structure and properties of surface and subsurface defects in graphite accounting for van der Waals and spin-polarization effects

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