Search results for "Scanning Tunneling Spectroscopy"

Surface plasmon polariton propagation length: A direct comparison using photon scanning tunneling microscopy and attenuated total reflection

2001

The propagation of surface plasmon polaritons (SPP's) is studied using a photon scanning tunneling microscope (PSTM) and conventional attenuated total reflection (ATR). The PSTM experiment uses localized (focused beam) launching of SPP's at a wavelength of 632.8 nm. Propagation of the SPP is observed as an exponentially decaying tail beyond the launch site and the $1/e$ propagation length is measured directly for a series of Ag films of different thicknesses. The ATR measurements are used to characterize the thin film optical and thickness parameters, revealing, notably, the presence of a contaminating adlayer of ${\mathrm{Ag}}_{2}\mathrm{S}$ of typical dielectric function, $8.7+i2.7,$ and …

Quasiparticle interference of spin momentum locked surface states at step edges on Re(0001)

2020

Quasiparticle interference patterns formed by a surface state on the Re(0001) surface were investigated using scanning tunneling spectroscopy. The energy dispersion is inferred from Fourier-transformed differential conductivity maps for occupied and unoccupied states. The band dispersion for occupied states agrees with earlier published results obtained by angle-resolved photoemission spectroscopy. An analysis of the phase of interference patterns at step edges reveals a drastic change in the effective energy barrier for backscattering above and below the Fermi level. The attenuation of the interference pattern with increasing distance indicates interband scattering is the dominant scatteri…

Spin scattering and spin-polarized hybrid interface states at a metal-organic interface

2011

Spin scattering at the interface formed between metallic Fe and Cu-phthalocyanine molecules is investigated by spin-polarized scanning tunneling spectroscopy and spin-resolved photoemission. The results are interpreted using first-principles electronic structure theory. The combination of experimental and theoretical techniques allows us to shed light on the role of hybrid interface states for the spin scattering. We show that Cu-phthalocyanine acts, via hybrid interface states, as a local spin filter up to room temperature both below and above the Fermi energy, ${E}_{\mathrm{F}}$. At the same time, the molecule behaves as a featureless scattering barrier in a region of about 1 eV around ${…

Asymptotic and Numerical Studies of Resonant Tunneling in 2D-Waveguides for Electrons of Small Energy

2021

Chapter 5 is devoted to asymptotic studies of electron resonant tunneling in a two-dimensional waveguide with two narrows. The narrow diameter plays the role of a small parameter. The asymptotics of basic characteristics of resonant tunneling are presented for electrons with energy between the first and the second thresholds. Moreover, the asymptotics results are compared with numerical ones obtained by approximate calculation of the scattering matrix.

Tunneling in a ?breathing? double well: Adiabatic and antiadiabatic limits and tunneling suppression

1995

Tunneling in a piecewise harmonic potential coupled to a harmonic oscillator is considered by means of the path integral technique. The reduced propagator for the tunneling particle is calculated explicitly and the tunneling splitting is found in semiclassical approximation. The result holds for arbitrary values of the parameters of the system. From this the adiabatic and antiadiabatic approximations are obtained as particular cases and compared with the results obtained differently. The limit of a strong interaction is also considered. It is found that for strong interaction or equivalently for the harmonic frequency tending to zero the preexponential factor in the tunneling splitting tend…

Zero-bias conductance peak in detached flakes of superconducting 2H-TaS2probed by scanning tunneling spectroscopy

2014

We report an anomalous tunneling conductance with a zero-bias peak in flakes of superconducting 2$H$-${\mathrm{TaS}}_{2}$ detached through mechanical exfoliation. To explain the observed phenomenon, we construct a minimal model for a single unit cell layer of superconducting 2$H$-${\mathrm{TaS}}_{2}$ with a simplified two-dimensional Fermi surface and a sign-changing Cooper-pair wave function induced by Coulomb repulsion. Superconductivity is induced in the central $\ensuremath{\Gamma}$ pocket, where it becomes nodal. We show that weak scattering at the nodal Fermi surface, produced by nonperturbative coupling between tip and sample, gives Andreev states that lead to a zero-bias peak in the…

Control of single-electron tunneling by surface acoustic waves.

1994

Scanning tunneling microscopy and spectroscopy of Mo clusters grown on TiO2(110).

2007

Molybdenum was deposited in two steps (3 eq. ML and 1 eq. ML) on the light blue rutile TiO2 10) (1 x 1) surface at room temperature, each Mo deposition cycle being followed by an annealing up to 950-1000 K. This procedure was found to lead to formation of separated clusters having a size in very wide range (1-20 nm). Scanning tunneling microscopy showed a dependence of the cluster morphology as a function of the size. The scanning tunneling spectra of Mo clusters was studied as a function of cluster dimensions and discussed in comparison with photoelectron spectroscopy results previously obtained for homogeneous Mo films. The dI/d V curves do not display the valence band structure of deposi…

Imaging of surface plasmon propagation and edge interaction using a photon scanning tunneling microscope

1994

We report the direct imaging of surface plasmon propagation on thin silver films using the photon scanning tunneling microscope. It is found that the surface plasmon remains tightly confined in the original launch direction with insignificant scattering to other momentum states. A propagation length of 13.2 \ensuremath{\mu}m is measured at \ensuremath{\lambda}=632.8 nm. We also present images showing the interaction of a surface plasmon with the edge of the metal film supporting it. The most remarkable feature is the absence of specularly reflected beam.

Field-induced tip–sample oxygen transfer in scanning tunneling microscopy on TiO2(110) (1 1).

2008

International audience; A study on the field-induced tip–surface oxygen transfer at room temperature and its influence on the tunneling conditions for stable STM imaging of the TiO2(110) (1 1) surface is reported. A simple model of field-induced transfer is applied to tungsten and platinum–iridium tips. The oxygen transition rates from the sample to the tip or from the tip to the sample depend on the oxygen desorption barriers formed at tunneling distance. For stable imaging the applied bias voltage has to balance the oxygen transfer probabilities in both directions. In the case of Pt/Ir tips, the tunneling conditions for images with clear evidence of bridging oxygen point defects have been…