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Scanning tunneling spectroscopy

About: Scanning tunneling spectroscopy is a research topic. Over the lifetime, 7886 publications have been published within this topic receiving 213828 citations.


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Journal ArticleDOI
TL;DR: It is demonstrated that π paramagnetism of high-spin graphene flakes can survive on surfaces, opening the door to study the quantum behavior of interacting π spins in graphene systems.
Abstract: Graphene can develop large magnetic moments in custom-crafted open-shell nanostructures such as triangulene, a triangular piece of graphene with zigzag edges. Current methods of engineering graphene nanosystems on surfaces succeeded in producing atomically precise open-shell structures, but demonstration of their net spin remains elusive to date. Here, we fabricate triangulenelike graphene systems and demonstrate that they possess a spin S=1 ground state. Scanning tunneling spectroscopy identifies the fingerprint of an underscreened S=1 Kondo state on these flakes at low temperatures, signaling the dominant ferromagnetic interactions between two spins. Combined with simulations based on the meanfield Hubbard model, we show that this S=1 π paramagnetism is robust and can be turned into an S=1/2 state by additional H atoms attached to the radical sites. Our results demonstrate that π paramagnetism of high-spin graphene flakes can survive on surfaces, opening the door to study the quantum behavior of interacting π spins in graphene systems.

103 citations

Journal ArticleDOI
TL;DR: In this article, the authors measured electron tunneling via discrete energy levels in ferromagnetic cobalt particles that are less than 4 nm in diameter, using nonmagnetic electrodes.
Abstract: We measure electron tunneling via discrete energy levels in ferromagnetic cobalt particles that are less than 4 nm in diameter, using nonmagnetic electrodes. Because of magnetic anisotropy, the energy of each tunneling resonance shifts as an applied magnetic field rotates the particle's magnetic moment. We see both spin-increasing and decreasing tunneling transitions, but do not observe the spin degeneracy at small magnetic fields seen previously in nonmagnetic materials. The tunneling spectrum is denser than predicted for independent electrons, possibly due to spin-wave excitations.

103 citations

Book
10 Nov 1997
TL;DR: In this paper, the authors introduce uniform cantilevers with conversion tables, and show that the conversion tables can be represented by a V-shaped cantilever with a tip sample adhesion and a Tip Sample Force Curve.
Abstract: 1 Introduction. 2 Uniform Cantilevers. 3 Cantilever Conversion Tables. 4 V-Shaped Cantilevers. 5 Tip Sample Adhesion. 6 Tip Sample Force Curve. 7 Free Vibrations. 8 Noncontact Mode. 9 Tapping Mode. 10 Metal-Insulator-Metal Tunneling. 11 Fowler-Nordheim Tunneling. 12 Scanning Tunneling Spectroscopy. 13 Coulomb Blockade. 14 Density of States. 15 Electrostatics. 16 Near-Field Optics. 17 Constriction and Boundary Resistence. 18 Scanning Thermal Conductivity Microscopy. 19 Kelvin Probe Force Microscopy. 20 Raman Scattering in Nanocrystals.

103 citations

Journal ArticleDOI
TL;DR: Results suggest that a transition from a planar to the bulk-like ZnO structure occurs around the thickness of ZnL(4L), and demonstrate that the lattice constant and the band gap in ultrathin ZNO can be tuned by controlling the number of layers.
Abstract: Single and few-layer ZnO(0001) (ZnO(nL), n = 1–4) grown on Au(111) have been characterized via scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and density functional theory (DFT) calculations. We find that the in-plane lattice constants of the ZnO(nL, n ≤ 3) are expanded compared to that of the bulk wurtzite ZnO(0001). The lattice constant reaches a maximum expansion of 3% in the ZnO(2L) and decreases to the bulk wurtzite ZnO value in the ZnO(4L). The band gap decreases monotonically with increasing number of ZnO layers from 4.48 eV (ZnO(1L)) to 3.42 eV (ZnO(4L)). These results suggest that a transition from a planar to the bulk-like ZnO structure occurs around the thickness of ZnO(4L). The work also demonstrates that the lattice constant and the band gap in ultrathin ZnO can be tuned by controlling the number of layers, providing a basis for further investigation of this material.

102 citations

Journal ArticleDOI
01 Nov 1989-Nature
TL;DR: In this paper, negative differential conductivity on particular binding sites of a Si (111) surface doped with boron was observed at 1.4 V tip bias at a specific type of site.
Abstract: THE tunnel diode1, which is widely used in high-speed electronics applications2, depends on the property of negative differential conductivity, that is, a negative slope in the current–voltage curve. The mechanism underlying the tunnel diode's behaviour, namely the existence of a range of biases for which tunnelling is forbidden or suppressed following a bias for which tunnelling is strongly favoured, has been employed subsequently in the design of new devices that also display the conductance anomaly, such as the double-barrier resonant-tunnelling device3. It has been predicted4 that the conductance anomaly could result from a similar mechanism at the tunnel junction of the scanning tunnelling microscope (STM), where localized states on adsorbate and tip atoms give rise to allowed and suppressed energies for tunnelling. The STM has the capability to image regions of negative differential conductivity induced by individual atoms on a surface. Here we report the observation of negative differential conductivity on particular binding sites of a Si (111) surface doped with boron. Specific current–voltage characteristics are shown to be related to the presence or absence of the dopant at individual atomic sites, and negative differential conductivity is observed at –1.4 V tip bias at a specific type of site. Tunnelling spectroscopy indicates that the effect results from a tunnel-diode mechanism.

102 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202345
202289
2021128
2020143
2019134
2018159