Search results for "Scanning tunneling microscopy"
showing 10 items of 21 documents
Individual arc-discharge synthesized multiwalled carbon nanotubes probed with multiple measurement techniques
2020
Arc-discharge synthesized multiwalled carbon nanotubes (AD-MWNT), or related MWNTs, exhibit a good quality compared to the more common type of MWNT synthesized by catalytic chemical vapor deposition methods. Yet experimental measurements on these are rather few and typically have not correlated data from different measurement techniques. Here, the authors report Raman spectroscopy, scanning probe microscopy, conductivity measurements, and force microscopy on single AD-MWNTs. The results demonstrate the high quality of AD-MWNTs and are compatible with the view of them as the best approximation of MWNTs as an assembly of defect-free concentric individual single-walled carbon nanotubes. The au…
Visualization of Moiré Magnons in Monolayer Ferromagnet
2023
| openaire: EC/H2020/788185/EU//E-DESIGN Two-dimensional magnetic materials provide an ideal platform to explore collective many-body excitations associated with spin fluctuations. In particular, it should be feasible to explore, manipulate, and ultimately design magnonic excitations in two-dimensional van der Waals magnets in a controllable way. Here we demonstrate the emergence of moiré magnon excitations, stemming from the interplay of spin-excitations in monolayer CrBr3 and the moiré pattern arising from the lattice mismatch with the underlying substrate. The existence of moiré magnons is further confirmed via inelastic quasiparticle interference, showing the appearance of a dispersion …
Probing large area surface plasmon interference in thin metal films using photon scanning tunneling microscopy.
2003
Abstract The interference of surface plasmons can provide important information regarding the surface features of the hosting thin metal film. We present an investigation of the interference of optically excited surface plasmons in the Kretschmann configuration in the visible spectrum. Large area surface plasmon interference regions are generated at several wavelengths and imaged with the photon scanning tunneling microscope. Furthermore, we discuss the non-retarded dispersion relations for the surface plasmons in the probe–metal system modeled as confocal hyperboloids of revolution in the spheroidal coordinate systems.
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 …
Temperature-driven spin reorientation transition inFe∕Mo(110)nanostructures
2007
Using low-temperature spin polarized scanning tunneling microscopy and spectroscopy, we observed a temperature-driven spin-reorientation transition (SRT) in Fe double layer (DL) nanostructures grown by step-flow growth on Mo(110). Magnetization components along the vertical and horizontal directions were detected with $4∕16$ ML Co∕10 ML $\mathrm{Au}∕\mathrm{W}(110)$ tips with out-of-plane (4 ML Co) and in-plane (16 ML Co) magnetic sensitivities. The magnetic easy axis of the Fe DL nanostructures continuously rotates from the vertical direction at $5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ to an in-plane direction at $20\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The rotation angle is independent …
Moir\'e-enabled topological superconductivity
2020
The search for artificial topological superconductivity has been limited by the stringent conditions required for its emergence. As exemplified by the recent discoveries of various correlated electronic states in twisted van der Waals materials, moir\'e patterns can act as a powerful knob to create artificial electronic structures. Here, we demonstrate that a moir\'e pattern between a van der Waals superconductor and a monolayer ferromagnet creates a periodic potential modulation that enables the realization of a topological superconducting state that would not be accessible in the absence of the moir\'e. The magnetic moir\'e pattern gives rise to Yu-Shiba-Rusinov minibands and periodic mod…
Optical properties of biocompatible polyaniline nano-composites
2006
Abstract Polyaniline (PANI) is an electro-active polymer of great interest thanks to its outstanding physical and chemical properties which make it suitable for various applications in optics, bioelectronics, biosensors, diagnostics and therapeutic devices. Unfortunately, PANI is infusible and insoluble in most common solvents and, thus, very difficult to process. In the attempt of improving processability, yet preserving its interesting properties, PANI has been synthesized in the form of particles and dispersed into a hydrogel matrix. The synthesis of PANI–hydrogel composites proceeds via γ-irradiation of PANI dispersions as obtained by ‘in situ’ polymerization of aniline in the presence …
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…
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.
Resolution of the photon scanning tunneling microscope: influence of physical parameters
1992
Abstract The photon scanning tunneling microscope (PSTM) is the photon analogue of the electron scanning tunneling microscope (ESTM). It uses the evanescent field due to total internal reflection (TIR) of a light beam in a prism modulated by a sample placed on the base of the prism. Our experimental results shown details which present a lateral size as small as 200 A. The PSTM axial resolution is more difficult to evaluate. It is a function of the roughness of the sample. For very smooth samples, images shown an axial resolution of about 10 A. At last we discuss how both lateral and axial resolution can be affected by several parameters such as the tip surface distance and the roughness of …