1. Introduction 2. Theoretical foundations 3. Propagation and focusing of optical fields 4. Spatial resolution and position accuracy 5. Nanoscale optical microscopy 6. Near-field optical probes 7. Probe-sample distance control 8. Light emission and optical interaction in nanoscale environments 9. Quantum emitters 10. Dipole emission near planar interfaces 11. Photonic crystals and resonators 12. Surface plasmons 13. Forces in confined fields 14. Fluctuation-induced phenomena 15. Theoretical methods in nano-optics Appendices Index.

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Principles of nano-optics

Resistive switching in transition metal oxides

This article reviews the progress of atomic force microscopy in ultrahigh vacuum, starting with its invention and covering most of the recent developments. Today, dynamic force microscopy allows us to image surfaces of conductors and insulators in vacuum with atomic resolution. The most widely used technique for atomic-resolution force microscopy in vacuum is frequency-modulation atomic force microscopy (FM-AFM). This technique, as well as other dynamic methods, is explained in detail in this article. In the last few years many groups have expanded the empirical knowledge and deepened our theoretical understanding of frequency-modulation atomic force microscopy. Consequently spatial resolution and ease of use have been increased dramatically. Vacuum atomic force microscopy opens up new classes of experiments, ranging from imaging of insulators with true atomic resolution to the measurement of forces between individual atoms.

https://hep.physics.utoronto.ca/WilliamTrischuk/courses/phy189/AFM_revmodphys.pdf

Advances in atomic force microscopy

Dynamic atomic force microscopy methods

Large-scale superconducting electric devices for power industry depend critically on wires with high critical current densities at temperatures where cryogenic losses are tolerable This restricts choice to two high-temperature cuprate superconductors, (Bi,Pb)2Sr2Ca2Cu3Ox and YBa2Cu3Ox, and possibly to MgB2, recently discovered to superconduct at 39 K Crystal structure and material anisotropy place fundamental restrictions on their properties, especially in polycrystalline form So far, power applications have followed a largely empirical, twin-track approach of conductor development and construction of prototype devices The feasibility of superconducting power cables, magnetic energy-storage devices, transformers, fault current limiters and motors, largely using (Bi,Pb)2Sr2Ca2Cu3Ox conductor, is proven Widespread applications now depend significantly on cost-effective resolution of fundamental materials and fabrication issues, which control the production of low-cost, high-performance conductors of these remarkable compounds

High-Tc superconducting materials for electric power applications.

The atomic force microscope images surfaces by sensing the forces between a sharp tip and a sample. If the tip-sample interaction is dominated by short-range forces due to the formation of covalent bonds, the image of an individual atom should reflect the angular symmetry of the interaction. Here, we report on a distinct substructure in the images of individual adatoms on silicon (111)-(7x7), two crescents with a spherical envelope. The crescents are interpreted as images of two atomic orbitals of the front atom of the tip. Key for the observation of these subatomic features is a force-detection scheme with superior noise performance and enhanced sensitivity to short-range forces.

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Subatomic Features on the Silicon (111)-(7×7) Surface Observed by Atomic Force Microscopy

With the discovery of high-temperature superconductivity1, it seemed that the vision of superconducting power cables operating at the boiling point of liquid nitrogen (77 K) was close to realization But it was soon found that the critical current density Jc of the supercurrents that can pass through these polycrystalline materials without destroying superconductivity is remarkably small1,2 In many materials, Jc is suppressed at grain boundaries2,3,4, by phenomena such as interface charging and bending of the electronic band structure5,6,7,8,9 Partial replacement (‘doping’) of the yttrium in YBa2Cu3O7-δ with calcium has been used to increase grain-boundary Jc values substantially, but only at temperatures much lower than 77 K (ref 9) Here we show that preferentially overdoping the grain boundaries, relative to the grains themselves, yields values of Jc at 77 K that far exceed previously published values Our results indicate that grain-boundary doping is a viable approach for producing a practical, cost-effective superconducting power cable operating at liquid-nitrogen temperatures

Enhanced supercurrent density in polycrystalline YBa2Cu3O7-δ at 77 K from calcium doping of grain boundaries

Calculation of the optimal imaging parameters for frequency modulation atomic force microscopy

The critical current density of grain boundaries in YBa2Cu3O7 − δ films is increased beyond the hitherto established limit by overdoping the superconductor. Using Ca-doping, values for the critical current density are obtained, that exceed the highest values reported ever for the undoped material by more than a factor of seven. Further, it is found that the overdoping strongly reduces the grain boundary normal-state resistivity. This systematic improvement of the grain boundary transport properties by doping is of great importance for applications of the high-Tc cuprates and gives insight into the mechanisms controlling the grain boundary behavior.

https://iopscience.iop.org/article/10.1209/epl/i1999-00359-2/pdf

Doping-induced enhancement of the critical currents of grain boundaries in YBa2Cu3O7 − δ

Frequency modulation atomic force microscopy is a method for imaging the surface of metals, semiconductors and insulators in ultrahigh vacuum with true atomic resolution. The imaging signal in this technique is the frequency shift $\ensuremath{\Delta}f$ of an oscillating cantilever with eigenfrequency ${f}_{0},$ spring constant k and amplitude A, which is subject to tip-sample forces ${F}_{\mathrm{ts}}.$ Here, we present analytical results of $\ensuremath{\Delta}{f(f}_{0},k,A)$ for several basic classes of ${F}_{\mathrm{ts}}.$ With these results, a method to calculate images is derived and demonstrated with an example.

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H. Bielefeldt

Papers

Subatomic Features on the Silicon (111)-(7×7) Surface Observed by Atomic Force Microscopy

Enhanced supercurrent density in polycrystalline YBa2Cu3O7-δ at 77 K from calcium doping of grain boundaries

Calculation of the optimal imaging parameters for frequency modulation atomic force microscopy

Doping-induced enhancement of the critical currents of grain boundaries in YBa2Cu3O7 − δ

Physical interpretation of frequency-modulation atomic force microscopy