INFLUENCE OF A TIP/SAMPLE INTERACTION ON SCANNING TUNNELING SPECTROSCOPY DATA

1995 ◽  
Vol 02 (02) ◽  
pp. 219-223 ◽  
Author(s):  
V.G. ZAVODINSKY ◽  
I.A. KUYANOV
Keyword(s):  
Electronic Structure ◽  
Local Density ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Local Density Of States ◽  
Tunnel Current ◽  
Free Sample ◽  
Discrete Variational Method ◽  
Local Electronic Structure ◽  
Sample Distance

The electronic states and the tunnel current for the W/Si and W/Al tip/sample systems were calculated by the first-principles discrete-variational method of the local-density approximation. It was found that the local-electronic structure of the Si surface resembles that of a free sample even for the tip/sample distances of 2–3 Å. The electronic structure of the Al surface is more sensitive to the tip/sample interaction and approaches the free surface form when the tip/sample distance is larger than 4 Å. The local density of states of the W tip also depends on the tip/sample distance and must be taken into account in the tunnel-current calculations and in the interpretations of the STS data.

Local Electronic Structure in Ordered Aggregates of Carbon Nanotubes: Scanning Tunneling Microscopy/scanning Tunneling Spectroscopy Study

1998 ◽  
Vol 13 (9) ◽  
pp. 2389-2395 ◽  
Author(s):  
D. L. Carroll ◽  
P. M. Ajayan ◽  
S. Curran
Keyword(s):  
Carbon Nanotubes ◽  
Electronic Structure ◽  
Scanning Tunneling Microscopy ◽  
Local Density ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Spatially Resolved ◽  
Local Electronic Structure

The recent application of tunneling probes in electronic structure studies of carbon nanotubes has proven both powerful and challenging. Using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS), local electronic properties in ordered aggregates of carbon nanotubes (multiwalled nanotubes and ropes of single walled nanotubes) have been probed. In this report, we present evidence for interlayer (concentric tube) interactions in multiwalled tubes and tube-tube interactions in singlewalled nanotube ropes. The spatially resolved, local electronic structure, as determined by the local density of electronic states, is shown to clearly reflect tube-tube interactions in both of these aggregate forms.

Measurement of Local Density of States by Scanning Tunneling Spectroscopy at Low Temperature

1987 ◽  
Vol 26 (S3-1) ◽  
pp. 627 ◽  
Author(s):  
Hiroshi Bando ◽  
Hiroshi Tokumoto ◽  
Wataru Mizutani ◽  
Kazuhiro Endo ◽  
Shigeru Wakiyama ◽  
...  
Keyword(s):  
Low Temperature ◽  
Density Of States ◽  
Local Density ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Local Density Of States

Single-walled carbon nanotubes synthesized by the pyrolysis of pyridine over catalysts

2006 ◽  
Vol 21 (11) ◽  
pp. 2835-2840 ◽  
Author(s):  
J. Liu ◽  
D.L. Carroll ◽  
J. Cech ◽  
S. Roth
Keyword(s):  
Carbon Nanotubes ◽  
Nitrogen Doping ◽  
Doping Concentration ◽  
Local Density ◽  
Single Walled Carbon Nanotubes ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Local Density Of States ◽  
Single Walled Carbon ◽  
Walled Carbon Nanotubes

Single-walled carbon nanotubes (SWNTs) were successfully synthesized by pyrolysis of pyridine over MgO supported Fe–Mo or Co–Mo catalysts in the presence of pure H2 or a mixture of H2 and NH3 atmospheres. The average diameters of SWNTs are ∼1.5 and ∼3 nm for pure H2 and the H2 and HN3 mixture, respectively. Scanning tunneling spectroscopy (STS) studies show that the SWNTs grown in both atmospheres are doped with nitrogen substituted into the lattice in a pyridine-type structure. This results in a donor feature in the local density of states with an energy that depends on the nitrogen doping concentration.

Electronic States and Mixing of Different Symmetry or Antiferromagnetism in Vortex Cores in dx2-y2-wave Superconductivity

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3560-3565 ◽  
Author(s):  
MASAO OGATA
Keyword(s):  
Density Of States ◽  
Vortex Core ◽  
Local Density ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Local Density Of States ◽  
Zero Energy ◽  
The Core ◽  
Gutzwiller Approximation ◽  
Energy Peak

The microscopic structure of vortices in high-Tc superconductors is studied using the two-dimensional t-J model. The spatial dependences of order parameters are determined self-consistently using the Gutzwiller approximation, in which the effect of correlation is into account. In the high-doping region, the pair potential has d x2-y2-wave nature and the local density of states in the vicinity of the core shows a zero-energy peak. However, in the low-doping region, a spatially oscillating (extended) s-wave-type order parameter is locally induced around the vortex core. As a result, the local density of states near the core shows a splitting of the zero-energy peak. This gives a possible explanation for the experimental data of scanning tunneling spectroscopy for YBCO. The possibility of the antiferromagnetic vortex core is also studied by modifying the Gutzwiller approximation. It is found that, close to the boundary to the antiferromagnetically ordered state, the antiferromagnetic correlation develops inside the vortex core, even if the bulk state is the pure d-wave state. In this case the local density of states near the core does not have a zero-energy peak but instead shows a gap-like feature, which can be observed experimentally. Finally the sign change of the charge of the vortex core as a function of the doping rate is found.

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