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Magnetic properties as a function of film thickness (2-55 nm) for magnetite ([Fe.sub.3] [O.sub.4]) thin films grown on MgO (100) substrates show that the small thickness films ([less than or equal to] 5 nm) are ferromagnetic and possess magnetization values which are much greater than that of bulk [Fe.sub.3] [O.sub.4]. The inverse thickness dependence of the magnetization points to an interface related mechanism. Whereas, our detailed spin polarized density functional theoretical calculations suggests that there is only a marginal enhancement in the local spin moments of Fe-atom in the vicinity of the [Fe.sub.3] [O.sub.4]-MgO interface and it turns out that the noncompensation of spin moments between the two magnetic sublattices of spinel [Fe.sub.3] [O.sub.4 ]is a major factor contributing to the enhancement of magnetization. Index Terms--Epitaxial layers, interface phenomena, magnetite, surfaces.

A study is conducted to show that the films grown on MgO (100) substrate remain fully coherent up to much greater thickness than predicted by the FKR model (70 nm) from the strain relaxation studies of epitaxial Fe3O4 thin films grown on MgO (100) substrates. The observed strain relaxation behavior is attributed to the differences in the crystal structure symmetry between MgO and Fe3O4.

In this paper, we propose methods for the measurement of electric intensities of a microwave field above the surface of microwave circuits. Using miniaturized coaxial antennas, we measure all spatial components of the induced field above device-under-test. A special position/signal difference method is used to better localize the measured field and increase the spatial resolution of the field mapping. During the scanning process, the antenna is driven at the defined distance above the sample surface according to previously acquired topographic data. For measurement of the tangential-field components parallel to the sample surface, the antenna is tilted by approximately 45[degrees] relative to the sample surface. By its rotation about the vertical axis, various components of the field are measured, and vertical and horizontal electric-field intensities are recalculated. The probes are calibrated in a well-defined field standard and allow good quantitative characterization of the measured field. Index Terms--Coaxial antennas, near-field measurements, scanning near-field microscopy.

Research is conducted to demonstrate the polarization properties of light in reflection-mode scanning near-field optical microscopy (SNOM) to better understand the mechanisms of its effects. Another objective is to examine whether the resolution and contrast can be further enhanced through optical detection with polarization analysis. Results show that the polarization state of light from SNOM can be changed using a metal surface. Metal pattern images on glass also show strong polarization contrast.

A study was conducted to determine the imaging mechanisms involved in the reflection-mode scanning near-field optical microscopy (R-SNOM), particularly the gap-width dependence of the optical signal utilized for producing images. It was believed that image artifacts of SNOM imaging samples were caused by the coupling between optical signal and topography. Results indicated that R-SNOM images relied on the tip shape and the polarization state of light and high resolution images of magnetic bits were produced on a topographically flat magneto-optic sample.

A technique that is easy to implement and sensitive for measuring lateral oscillation amplitudes of optical fibers on the nanometer scale for shear-force microscopy is described. The measurement system analyzed here is based on using the optical fiber tip as a cylindrical lens to focus and deflect a detection beam. It is shown that for our experimental arrangement, this technique is at least 2.5 times as sensitive as merely shadowing the edge of such a beam, as in most commonly used configurations. As a result, oscillation amplitudes of the order of 2-3 nm may easily be measured. An advantage of this system is that absolute vibration amplitudes are easily measured. A simple geometric model is used to describe the operation of the system.

Shear-force imaging which is usually applied for distance regulation in scanning near-field optical microscopy was found to be an unreliable method for accurate topographic measurements. This is due to the variation of shear-force damping in various materials. Findings for the shear-force damping properties for various materials are shown. Results also indicated that there are at least two distinct shear force damping mechanisms and that damping properties are related to the islands' size on glass substrates.

The operation of spin-polarized scanning tunneling microscopes (STM) come with the problems of magnetostatic interaction and magnetostriction. These problems can be avoided with the use of Cr, MnNi and MnPt antiferromagnetic tips. The results show that using these materials can produce low-energy electron diffraction patterns. Antiferromagnetic materials can be used as STM tips to obtain atomic resolution images.

The topographic and magnetic surface structure of a natural single crystal of magnetite ([Fe.sub.3][O.sub.4], a common mineral, has been studied from the submicrometer scale down to the atomic scale with a scanning tunneling microscope having nonmagnetic tungsten as well as ferromagnetic iron probe tips. Several different (001) crystal planes were imaged to atomic resolution with both kinds of tips. A selective imaging of the octahedrally coordinated Fe B-sites in the Fe-O planes, and even a selective imaging of the different magnetic ions [Fe.sup.2+] and [Fe.sup.3+], has been achieved, demonstrating for the first time that magnetic imaging can be realized at the atomic level., THE SCANNING TUNNELING MICROscope (STM), developed by Binnig, Rohrer, Gerber, and Weibel [1], is already well known for its ability to image surface structures of conducting samples down to the [...]

Electron backscatter diffraction (EBSD) analysis and magnetic force microscopy are used for analyzing magnetite thin films grown on [001] oriented MgO substrates. The EBSD analysis has shown that misoriented grains remaining after the annealing step form small islands with a size of about 100 nm, where their size and distribution have corresponded well to the antiferromagnetic pinning centers within the magnetic domain structures.

The crystallographic orientation of magnetite ([Fe.sub.3][O.sub.4]) thin films was measured using electron backscatter diffraction (EBSD). Misorientation boundaries appear in maps of angular misorientation data. The distribution of misorientation angles changes after annealing the samples in air at 250[degrees] C. Most small-angle misorientations (< 5 [degrees]) are removed after one minute of annealing, whereas larger misorientations (as high as 60[degrees]) continue to persist. Index Terms--Crystal growth, electron microscopy, electron backscatter diffraction, magnetite, position measurement.